I think you're right. On both technical and glorious levels, we cannot imagine what the Kingdom will be like. I personally think that the streets of Gold in Revelation, which were by far not the only symbols of the Kingdom that the Bible uses, are metaphors to give us an idea of how things will be, and to help us now. I'm not going to argue why in this particular post, however, because that isn't of the essence. The truth of the matter is, everything we know is fallen and cursed, and the Kingdom will not be. Our flesh is fallen and cursed, but our bodies in the Kingdom will not be. The Kingdom will be nothing like what we know. Praise God for that.
Many of my brothers and sisters see the Kingdom as a large, eternal church service--and I have absolutely no objection to that. If our services are what they should be, this discription should be as accurate as we can get. Many see it as a great family reunion, and this isn't flawed, either. My own walk with God, however, brings about an aching for him that leads me to believe that, for me, the closest symbol of the Kingdom is a wife whose husband has been to war for years, and she is reunited with him. Or a child who has been separated from his father, and after a long wait is reunited with him. I think the Kingdom of heaven is much more personal than we make it out to be--while the Kingdom can be characterized as a church service, I think, rather than a place with a stage and a pulpit, it is more of a long awaited embrace--a whisper of "I love you...I've always loved you. I've missed you so much."
