I have been on a couple of RSVP cruises - Caribbean and Alaska. They have all been a blast, so much so that we book the next year's February Caribbean cruise while we are still the ship. We have made a lot of friends along the way and get together with them when we can off the ships even though we live in different states.
RSVP and Atlantis charter the whole ship and there won’t be any regular cruises. The ships range from 700 to 3,500 passengers and RSVP also does river cruises in Europe on smaller ships. The passengers are predominantly men and RSVP seems to attract a bit more women that Atlantis does. Friends and family also go along. On our last cruise a guy was there with his mom and she did her best to find him a husband while on the cruise.
The gay charters are big money for the cruise lines so they make sure that the crew is aware of the importance of the cruise. It is the regular crew, not a special gay crew. They love working on the gay charters anyway since it is a break from the usual routine and they will tell you that gay cruisers are much happier, pleasant and a lot of fun. I heard of a case on the last cruise when a bar tender was so overcome with the experience that he came out to his coworkers.
The people on a gay cruise are from all walks of life, all ages, all body shapes and from all over the world. There is very little attitude onboard and you can have a nice conversation with someone in the elevator going up 5 decks, or flirt ;) As for it being a bathhouse on a boat: that is not the case. No, people are not blowing each other around the Lido pool!. If you want to have fun it can be found. If you want to be romantic with your man you can do that too. If you want read a book in a quiet place you can do that too.
RSVP and Atlantis bring their own entertainment, DJs and equipment onboard. There are themed parties almost every day. Atlantis is a bit more hard core on the dance parties that can go till the sun comes up whereas on RSVP it ends a bit earlier but you will find another activities pre-lunch (unheard of on Atlantis!)
No, I am not a travel agent or employee of RSVP/Atlantis (RSVP is now owned by Atlantis). I am just a big fan.