I've always thought the focus on pure square feet to be a little silly, for a number of reasons. It's fine if you want to talk in generalities (1500 vs. 3000 vs. 6000) but I've been in spacious-feeling 1200sq ft houses and cramped 3000sq ft houses. The house I grew up in was a 3-story (2 + finished walkout basement) colonial but due to the layout where it was all carved up into small rooms, it felt cramped. There wasn't a room for four people to sit and watch TV comfortably all at the same time, for instance. There's also the fact that basements are usually not considered in the square footage, but change things dramatically, either with extra storage space, living space, or both. I'd rather live in a 1100 sq ft house with a basement than a 2500 sq ft house without one. Then there is a consideration of features; three separate 150 sq ft rooms (den, living room, family room) is probably less desirable than one 300 sq ft great room. And on and on and on.
Finally, I think people on here really get caught up in the difference between, say, 1000 sq ft and 2000 sq ft when it comes to things like utilities and taxes. There probably isn't a huge difference in a given area, it's more mental than anything else.
