I enjoy stripshows and private parties (with male performers) - male nudity has become an accepted (in fact almost expected) feature of hen parties and several other events.
CFNM on the beach is also a favourite, on holiday I love a casual afternoon in the sun with my husband nicely unwrapped for me. (It also means he has to do some nude sunbathing at home to get his all-over tan started)
For a third choice I'd say nude modelling. There can be a very enjoyable relationship between a naked guy and a female photographer, especially when she gives her instructions and doesn't shy away from telling him how she wants his penis positioned.
I like it where it looks amateur and casual, where the man is naked and serving the clothed women. Cocktail party scenes are great, or where the women are getting ready to go out and he's there to serve them and help them get ready.