Boy, a choice between Lake Erie and Canada? That's a tough one… The reason I didn't include Little Bay De Noc is because while it's a great fishery, I believe there are better places to take your son for the trip of a lifetime!
I think that a lot will depend on what you're looking for in a trip. Is it going to be an adventure in itself or is the trip going to be one where you're looking for numbers of big fish?
If you're looking for adventure, then I'd say head north across the border to Canada. But go knowing that Canada isn't magical and the fishing can be as tough (or tougher) than here in the states. But by the same token, there can be times when it's out of this world…I've been up there when I couldn't buy a bite, and then I've been up there when I had a limit of walleyes in less than thirty minutes!
A fly in would be a great way to spend time with your son and totally be alone in the wilderness. But then too, you're totally dependant on the weather. If you have crappy weather, it's going to be a miserable time as well….
IF you're looking for numbers of big fish, then I'd say head east for Lake Erie for a couple days. Timing is going to be important; the truely BIG fish are on the feed in the spring and fall. But unless the weather is totally off, you'll probably catch more walleyes and smallmouth in one day than almost any other place in the world.
I remember the first time I went to Lake Erie. We got there in early May and were told that the big females were all spawned out and had dispersed. All we'd catch now would be "small males." Well, their idea of small male walleyes and mine are two totally different things, because for the next two days, we loaded the boat with 17 – 25 inch MALE walleyes! It was a great trip and I'd love to get back there this year.
My suggestion would be to check out a couple sport shows, gathering up as much literature as you can. Then, you and your son sit down and go through all the brochures in the evenings. Sometimes the "research" is almost as much fun as the trip itself!
So head on out to the shows with a plan in mind. Talk to as many different places as you can, gather up all the brochures, and have fun!