One of my many fantasies has always been having a meeting with a married couple.  Age and body type are not that important, however, the more innocent and wholesome the wife appears.....the better.  For whatever reason, the husband has a desire to watch his wife perform fellatio on a stranger....in particular....an older man. 
The meeting would be short and sweet.  The couple would come to my hotel room, and after brief pleasantries and assurances that they both wanted to do this...the wife would get on her knees and go down on me.  To add to the erotic nature of my turn on, she would do this in front of a full length mirror, so she can watch my penis slide in and out of her mouth...and I could look into the mirror and get a profile view myself.  The husband could sit in a chair a couple of feet away, and would be free to do whatever he wished.....with himself.  After cumming in her mouth, I would thank them for the opportunity, and they would leave.