Hmm.... I don't usually play a Zelda unless I'm going along with the story... but I DO sometimes do certain pastime things...
Such as, I will boot up WW to play the Sliding Puzzles. In MM, I'd probably do the Shooting galleries for fun. (haven't yet)
For MM, I'd probably also Swim around as a Zora for an extended amount of time.
Oh, and there's also Fishing in OoT and TP.
I used to Fish as a pastime for Okami. :nod:
Other than that, I can't think of any other "pastimes" I'd do :/