Let me just ask a question or two to try to get my mind straight on all this. It seems to me to be an important issue. Does everyone agree with robindegen that using models for buildings will compile faster than blocks? I understand that models don't work as well for collision detection, right?
But what about the fps when the game is running? What is the trade-off there? Do models slow down gameplay? Would it make any sense to make the first floor of a building out of blocks, then drop the rest of the skyscraper on top as a model? The first floor would have good collision detection, and the model would just be there for looks? Does it make sense to use models for buildings if you can't get up next to them?
I have built some fairly large levels out of blocks, and am hitting some FPS and build-time issues, and have not much in the way of NPC's added. So some discussion of this would be helpful.