I think Michigan would be lovely, but just to put in a plug for Branson, if you haven't been there before you might be pleasantly surprised. In all seriousness, I went kicking and screaming there for a family reunion/50 wedding anniversary about 15 years ago and had more fun than I had planned to (I was surly young adult at the time). We stayed in rental cottages on Tablerock Lake, spent most of time on the lake. We did have a boat....I'm sure there are rentals.
I don't remember toddler activities per se, but we did have a little one (he was probably about 1) with us. Fwiw, the branson walmart had the largest selection of organic produce i had ever seen. I also remember that we were able to rent a restaurant/banquet facility close by for the anniversary dinner, a bunch of folks came to that beyond just the immediate family that was vacationing together.
~ Dawn
Our little monkey (4/2011) & his early holiday present 12/12