Often I spin a fantasy that then gets used in one of my Lush stories.
I can't really say that I have a specific fantasy I keep going back to. More often than I'm willing to admit, it's inspired by something I read, watch, or otherwise view. However, I do come up with my own scenarios from time to time. That is what inspires my stories.
i usually think about the one night stand I had with a fellow college student in the bedroom of one our professors as she was caring for his house. She wanted to be on top...and it was a ride I won't forget :-)