Suggestions for gift certificates or tickets in NYC?

[candy]

My in-laws live moved to the NYC metro area a few years ago and hoped to take advantage of easy trips in and out of the city. It's been a few years now, life got in the way, and they can count their trips into the city on one hand. I'd like to buy them a gift certificate to a restaurant, or tickets to something, that will encourage them to hop on the train and do something fun.

Does anyone have suggestions? I'm kind of stumped because some of the obvious things (e.g. Broadway tickets) probably aren't their cup of tea. But I bet some of you can come up with ideas that never would have occurred to me. Many thanks in advance!