Prostitute scenes should be kind of bland. I haven't come across any chances yet, but random encounters don't need to be anything special. However, when it comes to characters that you spend some time with, go on quests on and such, there should be something interesting to go along with it. Interesting locations or something. I don't see a need for going crazy with random positions and all that. It's unnecessary. The lead up to getting Geralt laid is the more fun part.
Honestly, the elven bath scene isn't all that crazy. The lead up is the main attraction. Being in that location, the "bath" comment, Triss using magic to take off her clothes, Geralt being stunned and then fighting to take his clothes off. That stuff was great. The rest of it is kind of comedic with the elves/dwarf talking about the tale of the place with Triss and Geralt going at it down below. The scenes with Geralt and Triss are actually quite short.