Canoe is a great choice. I have live in saint louis for 16 years (I am 18, now, so that doesn't count for that much). Lots of great camp sites, good hiking. There are some amazingly scenic places in MO. Springfeild, springfeild, kinda a dud city. Its really busy when the state senate and whatnot is meeting, but after that its a ghost town. Saint Louis has decent sports you can follow, if you are into that. We have a pretty good music scene in saint louis, also, at least in my opinion.
but MO is great for the outdoorsy type. I'd suggest you take a camping trip next weekend and do it often. Canoeing, as mentioned above, is hard to beat. Great bluffs on the rivers, nice cold water, clean water, you can drink most of it, if you drink near a spring. Heh. HUGE springs. I was canoeing with some friends, and this giant spring was on the left. Well, we weren't really ready for it, and when our boat got next to the spring, it almost capsized due to the huge current coming from the spring. It was a total shocker. I fell out into water that was way colder than I expected. Nothing like that to wake you up.
If you have a son, move to saint louis and send him to SLUH.