Hmm... the lady in the picture gives you a basic idea. From behind, she has a nice and plump, but high, ass. She does yoga regularly, which really keeps it in shape.
A guy who slept with her (see old thread about the play) claimed that she was "tight". I've never had the pleasure of confirming this.
Speaking of her rear end, here's a story you all may enjoy. A few months ago, Sue was taking a shower when I heard a loud "Oww!" from the bathroom, then she yelled for me to come in. I came in to the bathroom and asked she what needed, and she yelled "Open the door!"
When I slid the door open, it was quite a sight. Sue was bent over, as if grabbing her ankles, with her rear end stuck in the air. Not only could I see everything -- labia, vagina, clit, EVERYTHING -- I could have taken my dick out right there and started fucking her. That seemed out of the question, though, so I had literally no idea what to do next.
Sue yelled again, "Come on, help me the fuck up!" Then it really got awkward. All I could think to do was press against her from behind (as if screwing her with my pants on), then pull on her shoulders to straighten her out.
Then she thanked me and I left.
Sue was bright red when she came down to make dinner.
She explained that she had bent over to pick up a shampoo bottle that had fallen, when she got a cramp in her back and couldn't stand up. It seemed a bit fishy, but I'll have to take her word for it.