I am pretty old compared to what I have read here. My Dad bought me the Hospital set
http://www.peeron.com/inv/sets/363-1 and quite a few others back in the mid 70's. I kept them, and on occasion, I would bring my bin out and figure out the right furniture placement for our "new" house (a real house). Once I got the furniture placement figured out with Lego, they would go back in their bin. Or, I would make a small castle.
My brother gave my son a Lego trike thing for Christmas '06, and I brought out my small bin of Lego. We all had fun for hours, and that was my enlightening. It seemed that I could only build with what I had- from a small 70's collection. The same space stuff, the same castle, the same house. This was frustrating, so I came out of my Dark Ages, and started buying. Buy, buy, buy, I did! Garage sales, Estate sales, Ebay, etc.
Funny, now that I have (what seems like) an endless supply, I now know nothing! I don't know what to build. While before, I could build a very creative thing with my old collection, now I can build nothing. I've even read books about building, yet have no more creative ideas. My brain feels too old to absorb the new pieces and techniques that have emerged since I was a kid. Cafe Corner was a great build, but I don't know if I could come up with that myself, or much less anything so creative.
I think it is better to operate at a deficit. It challenges the imagination, and forces solutions.