The popular imagination paints 'heaven' as some sort of place with clouds and blues and odd lights. But we confess merely that we believe in the Resurrection, that there is continuity between what the present is and what the future will be. It will be "better" -- redeemed, matured, and so on -- but there is no reason to think that there won't be Best Buy and San Diego, CA in the Resurrection. There's no reason to think we won't have guitars and houses and cheeseburgers.
Heaven is not the hope of the Christian. It is not our final destination. It is not what we should be striving towards. The Resurrection is the hope of the Christian and a renewed and redeemed earth is our final destination. I highly recommend anyone who is interested to read NT Wright's Surprised by Hope on this subject.
I think that today's Christianity focuses too heavily on "going to Heaven" when you die, and not enough on the true hope of our faith, the Resurrection, which Jesus Christ initiated 2,000 years ago. True "Heaven" is the perfect, eternal state described above in Revelation 21-22, not floating about on a cloud playing a harp. 'Heaven' comes to an Earth-reborn and all is set to rights - sin and death are destroyed forever. This is our true hope!
I don't know what state a Christian is in from death until the Resurrection; I don't think the scriptures are particularly clear on that. A lot of the text is taken out of context to describe the intermediate state, when actually it applies only to the eternal Resurrected state. My best guess is that the saints (physically deceased Christians) are somehow conscious and with Christ in some way. They may have some kind of heavenly body (their true body is raised at the Resurrection) or they may exist in some spiritual form, who knows?
Or they may simply be "asleep" until the Resurrection, as the Jews and early Christians understood it. By the writing of Revelation though (62 or 90AD, depending on if you are a partial-preterist or not) , the thought seems to have advanced to the point where the departed saints have a consciousness - in the vision John mentions the saints crying out, having white robes, etc. It may be metaphorical or it may be literal, though. After all, it's a "vision" not necessarily a photograph, as they say. An "impression" or an artist's rendition of an actual event, not a journalistically/scientifically accurate depiction.
Even if it's the former (consciousness and some kind of physical state), I believe the saints will still comprehend that the intermediate state is just that - intermediate. The true hope is the Resurrection, and while the departed saints aren't sinful anymore in their current state, they aren't whole yet either because all has not been put to rights yet. I believe that if the departed saints in the intermediate state are conscious, that they are able to see what is going on "down here", are able to worship and converse with Jesus and inquire as to the goings-on "down below", but they still don't have the full knowledge of what's going to happen next. The veil has been lifted, they don't live in the same cloud we do, but they are not all-knowing. The "portals" to perceive what's happening "down here" may come and go, or they may be constant, who knows. I've always wondered (if this notion is accurate) if my Christian ancestors (or anyone, for that matter), can "look down" and see me going to the bathroom, or farting when no one is around, or hear what I'm thinking at any given moment...or helping a stranger when no one else notices. I wonder how much they are shown, if anything. If they are even conscious.
The nearest analogy I can think of is someone who goes through a pitch-black maze successfully, then taken to a back room and allowed to watch through night-vision cameras another person attempt the same maze. They have a different view on things, but they can't intervene or communicate with the person, and they can't determine or predict the outcome. But they can discuss the maze with the Designer and inquire about why there is darkness, why it was made so difficult, etc.
In any case, the intermediate state between death for a Christian, and the final Resurrection will (if we are conscious for it) be infinitely better than life "on Earth", but still nothing compared to the future glory. Of that we can be sure.
If anyone has read Randy Alcorn's novels, I think he has a pretty biblical and sound grasp on all this, especially what the intermediate state is probably like. Take with a grain of salt - he's coming from a specific theological background (as we all are), and of course there are literary liberties taken, but on the whole it at least changed my perception of the state we as Christians are in when we pass and await the Resurrection.
As for "hell," fascinatingly enough, I don't think it being a place, condition or both (more than most dilemmas offer!) are even remotely close to telling the whole story. Even stranger, I don't think "neither" would really do the trick either. If I had to attempt to consolidate the entire idea into one descriptive word, it might be an " 'un'place " by which I mean something similar to what C. S. Lewis meant when he named the antagonist in Perelandra the "unman". Whereas Weston became the Unman after everything that could be identified as human was summarily taken away, I think hell is sort of analagous to an "unplace" insofar as anything typically associated with "somewhere"--life, activity, people, surroundings, etc--is almost entirely absent. Hell is described in Scripture as being very nebulously located, as being the "outer darkness" (some "place" that is just "out there" where no one cares to look), as being associated with death and the grave ("places" no living, moving, acting soul knows anything about), etc. A place is where something is, but hell is defined by being apart, or rather, it can't be defined so much by where it is as much as it can by where it isn't. In that sense, it is very much unlike our concept of a location or a place, where we can give you directions or coordinates or some other method for finding it. Hell, however, we can only "locate" by giving a sense of general direction, "out there" in the darkness, "down there" in the grave, etc... and it's always associated with these kinds of ideas that typically connote ambiguity, hiddenness, unidentifiability, etc..
If it makes sense to talk about spiritual "places," dimensions in the spiritual realm seem to exist based on descriptions. There seem to be all four dimensions present in the spiritual realm in all recorded accounts of them. In fact existence in the spiritual realm implies that there be some form of dimensionality. Whether spiritual is something other than physical, yet with spatial dimensions (+ time) being mentioned, I really don't know all the answers, but to say the spiritual world exists is to say it has existence on a fundamental level. For it to exist, there must be dimensions in which it exists. In recorded visions and prophecies and such it seems to operate much in the same way the physical realm operates. It seems to me like its an almost separate set of dimensions with definite relationship to each other. Almost as if it is a realm in the physical that we cannot normally interact with.
Still, I find it hard to comprehend the spiritual world in any kind of literal, physical framework, of the sort which would have such things as dimensions and directions. Maybe it's just me, but I don't really think that the archangel Michael was literally running the gauntlet through Persia on his way to Daniel, in the Frank Peretti sense, was he? Is heaven really "up", or hell really "down", or is that simply a symbolic understanding of where we are in the scheme of things...
Making sense of the Biblical imagery used for heaven and hell, then, in a "not-quite-literal" sense, heaven is the place characterized by perfection, beauty, wholeness, joy, healing, life, justice and peace (shalom!). It's symbolic. It's where everything that is wrong down here is gone, and everything that is right is even more right. And Hell, then, is the outer darkness. It is where every dim little light that shines in this fallen world is absent. Where even hope for the future is gone. Where we are tormented with that loss, that hopelessness, that never-ending guilt, in a way that "eternal flame" only scratches the surface of. It is being gone from the rest of Creation in every meaningful way.
By the way, an interesting book on the subject of hell and judgment is Brian McLaren's The Last Word, and the Word After That, which is the third book in the "New Kind of Christian" trilogy.
Just as one of the characters in the book, I would challenge us all to study not only the doctrine of hell over the history of the church, but also the history of the doctrine of hell over the history of the church, and indeed the history of hell (or the afterlife, judgment, etc.) over the course of human history, from the Babylonians to the Greeks to the Romans to the Jews and so on. It was really interesting to see how our understanding (as humans and as Christians) has evolved over the centuries and millenia.
A lot of our conceptions about what hell is like, I'm afraid, are more informed by Dante's Inferno and pop culture than by the historical, social, and religious contexts the scriptures were written and compiled in. In other words, I'm afraid a lot of the time we apply our 21st -century understandings and "baggage" when it comes to hell (or any other topic for that matter) to the first-century context and wonder why it doesn't fit.
To sum up, as I heard Tim Keller say recently, "I think that the 'hellfire and brimstone' imagery is certainly metaphorical. The reality is undoubtedly much, much worse".