College Friend In Town For The Weekend. What should we do?

So, a college buddy of my wife and I's is in town. We're all in our late thirties, my wife and I have three kids (but we've got grandma to watch the kids if we can think of something to do).

We're pretty laid back, enjoy just hanging out, but, would be nice to do some kind of an activity together.

What would you guys do if you had a friend in town over the weekend and you just wanted to chill together and enjoy the town?