Voyeurism
If you're really into voyeurism and are up to a bit of travel, head to Germany or the Netherlands and go to a "partytreff" or a "swinger club" that caters to/allows entry by singles as well as couples.
If you search the web for "partytreff" and "germany" you'll find no shortage of them (for example, search for Swingerclub Beverly in Solingen or Partytreff Mettman in Mettman, both of which accept single men). These types of places are discussed in quite a bit of detail on the wsg* board.
Although the idea is that you participate in the activities there is absolutely no pressure on anyone to do anything. If you want to just watch then everyone's cool with that. Of course you may be expected to be partly clothed or nude at the time as well.
I stopped and checked out the Beverly Club a few years ago when I happened to be passing through the area. I had injured my back a few days before and was in a lot of pain so wasn't able to participate. Despite the pain, I couldn't resist the temptation to stop and check it out after hearing about it from some friends. There are no "paid" girls at Beverly as it is strictly a "swinger" club. It's quite the facility and has a fairly large bar area, a dining room, and many "activity rooms". I was there on "dessous" night, which meant the ladies wore lingerie and men had to wear black underwear. I had a bite to eat and a beer and then went to one of the rooms that had a padded floor (the whole floor was made of 4" foam covered by vinyl) to lay down and ease the pain in my back. I had just laid flat on my back when two guys and a girl came in and started to have sex right next to me on the floor. I was invited to join in but had to decline because I was barely able to move due to back spasms. So, I just laid there and enjoyed the show. Every time a guy passed by the room the girl would invite him to join the others. I was amazed to see how many guys this girl could service at the same time - she had a voracious sexual appetite. I left before the action was over because there was so many people in the room they kept accidentally bumping me and sending spasms up my back. I hobbled around and saw at least 4 other rooms (including one with an equipped "dungeon" and one with a sex chair suspended from the ceiling). Most of the rooms were being put to good use by couples, threesomes and moresomes - you could either join in if invited or just stop and watch or whatever. A true voyeur's paradise.
Oh yes - cost for the evening was 120 Euros (less than $200 Canadian). This price included entry, a buffet dinner, unlimited beer and beverages, and "action" that was only limited by your own desires (I had none that night) and the extent to which others invite you to join in (which depends on how outgoing you are).
And I could tell you about the time I was at an FKK club to get a massage from a RMT (paid 60 Euro to get in). While waiting, I was standing at the bar (still suffering from back spasms so I couldn't sit). Suddenly, the two nude ladies (one was gorgeous, the other merely beautiful) who were next to me started a heavy, fully interactive lezzie show right then and there to try to get me or some other guys interested in giving them some action. Alas, all I could do was watch that night.... Life is so unfair.