The following may not have been the "best" but it is definitely one of the better ones and very memorable.
Picked up a very pretty young woman hitchhiking. I had no clue she was a provider, but during our conversation during the ride, it came up. I gave her a ride home and got her phone number when I dropped her off. The next day I called her and picked her up, and we were going to go back to my place (the place where I was staying as I was away from my home town), but she had a better idea. We pulled over, and ended up doing it on a beach in the moonlight. About 30 feet from the highway, and maybe the same distance from the closest house. Great experience, but unfortunately since I was out of town, I never saw her again.