Staying up late--later than everybody around me--on a night when I don't have any obligations for the next day.
Going out for the day, buying a new RPG rulebook, going out for lunch, taking in a movie, and going out again for dinner at a place where I know the people, and can just relax and have a good time.
The former, knowing that the $60-70 it'll take to do so can actually be legitimately spared.
Knowing I've no outstanding bills.
Know that I've got good money coming in... Alright, so that's a 'supposed' simple pleasure, since I've never really experienced it.
Cuddling up with my girlfriend. Tickling said girlfriend gently; she'll lie there, tremble a bit, and giggle cutely.
Chatting with a friend who doesn't consider two guys talking about their favorite passtimes to be "gay."
Putting an extraordinarily obnoxious person in their place, and seeing everyone else around laugh at them... not me.
Hot sex.