How about Svetlana Kuznetsova? She is slightly more rounded than the other girls, but looks very impressive from the rear!
Saw her play Megan Shaughnessy (I called her Shaughnessy holland as she was as flat as the country). at Roland Garros last year. Am going to Flushing Meadows this September to check out more young tennis ladies!
I watched her at Wimbledon last year, and I thought she was fit. She has a nice body, I am a bit surprised she is not even in the top 10. Ashley Harkleroad should have been in there as well.