The OP said "summer" in his post: I love Chicago and DC, but not in summer weather. Both get muggy and hot as hell.

Ever been to Montreal?

We were there two summers ago, and the weather was much more pleasant than here in the mid-Atlantic region. We went to the biodome (can't think of the proper name) which is a great science center. The Olympic pool is open to the public. There's biking along the Lachine canal, plus ferry and tour boat rides. The art museum was fabulous, and runs programs for kids. Lots of lovely parks and gardens, and I think the zoo has a good reputation, although we didn't visit it ourselves. Time your visit right and you could see part of the international fireworks festival.

Plus, the CDN dollar is tanking against the USD, so you'd be ahead there.