Never been to the FKK's in the north Rheinland but DEFINITELY want to go there. Was going to go the BOOT show but never did the past two years. I hear the girls are more likely to be german than romanians and that the value is better in terms of rates/extras and quality of service and "optics" as the FKK'ers refer to the girl's looks.
If you can get by all the guys scolding you to RTFF (READ THE FUCKING FORUM) posts before asking, there is a lot of information here. But I'd recommend takin an hour or two to read them anyways to narrow down your questions remaining. You will get better responses than just a generic question.
Here is the ISG section on German FKK'
http://www.internationalsexguide.nl/forum/forumdisplay.php?275-Germany-FKK-Clubs