Welcome to membership, and soon to St. Louis. I'm new to living in St. Louis also, and so am looking forward to the answers to your questions on St. Louis area boating.
Here's what I do know:
1. Lake of the Ozarks is only called LOTO on OSO. In St. Louis it is call "The Lake" It is about 3 hours away, and that is where most power boaters from St. Louis go, if they can. That is where you find your waterfront restrants etc.
2. Most of the Mississippi River boating happens north of downtown, near Alton IL, probably close to the St. Charles area you mentioned. Some also boat on the Illoinis river in the same general area.
3. There are several other smaller lakes even closer than "the Lake" if you want water for a small boat or to ski.
4. You will get older, but you'll never feel any richer, even though that will happen also. You'll simply notice that what used to be major expenses have become normal expenses that you don't even think about, but you add additional bigger expenses that eventially become the normal etc etc. (This assumes you avoid debt and save your money and pay cash for your toys. It takes most people longer to get out of debt than it does to save their first $100,000. Okay, lecture over)
5. I find the weather to be a little warmer than Indianapolis. Not unlike Louisville.
So, when you getting married? And will you have to change your OSO name to RobMo when you move?