"In the USA, big is good."

Oh? Surely, generalizations are dangerous. There are SO many factors involved in what people admire, whether it be derrieres or paintings or pie......(And, as we just saw there are many cultural responses to the very words used to refer to the subject as well! *grin*...around the US, 'butt' is sorta loaded, but not terribly offensive, while 'bottom' is often used for mixed company, and 'ass' is often the choice for more ...ummm...explicit context. Funny, whenI was a kid, 'fanny' was common, and was a fairly polite term, but I almost never hear it anymore. Perhaps becoming aware of UK usage has moved it to the sidelines.)

I would argue that the most common 'choice of size' is contained in this collage (clearly not small, but not huge, either.) (took me all of 12.47 seconds to find using Google Images)..

   But I remember seeing in a list an entire internet newsgroup devoted to 'skinny'.

In the last analysis, what does it matter, as long as there is a selection for everyone when just looking, and that one does not complain about size in one's chosen partner.