This is actually a hard one for me. Err... no pun intended.
I love curves, but I don't like really big butts. It's kind of hard to describe the kind of balance a woman must have between a big and small butt. A woman who does light exercises, loves to dance, runs, or plays basketball typically doesn't need to worry because she usually has the right amounts of meat in just the right spots. The woman in the following video has the right curves, and boy does she know how to move it:
http://www.youtube.com/watch?v=8tuvwxiPmgM
To me, a woman needs a flat stomach and a muscular butt, not a flabby one. You know, not
too big, but just big enough to hug.