If the weather works, rent a bike or roller blades and ride the path along the gorge towards Niagara on the lake. Great views and scenery for the most part and even in summer there's minimal crowds. Bound to have a smile on your face at the end of it.

There's also a great golf course. Haven't played it myself but I've heard from quite a few that it's one of the better ones in Ontario and a great deal to boot. Heck - just take a lesson from the pro if you don't want to be out all day. I think it's called the Whirlpool course.

Niagara on the lake is a nice place for cultured dining or tea and a winery tour is pretty cool. We did a special private one few years on a promo and it was exceptional. Much more than I had imagined. This isn't the one we did but it sounds pretty good - http://www.crushtours.com/daily.html