Well, a personal favorite is on my knees, face pressed into the pillow... but that's not the most frequent. The most often would be on my back, knees bent, legs resting on someone's back, very relaxed.
For a little while, at least.

WW

__________________
"I wondered, am I a lesbian, am I straight, or bisexual? Then I realized that I am just a slut.
So where's MY parade?"

---Margaret Cho