Bowling is awesome, but we do it year round.
Here in Seattle, Summer means MINIGOLF. My wife and I are playing with a bunch of our friends in a minigolf league for the second year. The league is called Drinks on the Links, because they've set up a bar in the middle of the course, serving wine and beer. Along with buying booze so you get good and drunk, everytime you get a hole-in-one, you get a free beer.