I'd go to Branson and boat on Tablerock. The huge cigarette boats will eat your 20' bowrider alive. I know, we have one. Whene we go to LOTO we chuck our timeshare and stay in a little resort near the Camdenton area. (Around Ha Ha Tanka State Park) Even that area now is getting crowded.
I would try Tablerock. We own at Marriott too and this year will host a family reunion at our home resort, Horizons. We really wish it's on the water, but the consistant quality and the service, I don't think, can be found in Branson, except maybe Chateau on the Lake, which are just rooms.
I would like to add my two cents worth about the Branson Yacht Club. Never been there, but it is on Indian Point. We rented a slip down there one year and had to fight the Silver Dollar City traffic every time. One time it took about an hour to get there from town. If you stay down there, you won't have that problem, but it is pretty dense down there. We will rent a slip at the State Park Marina--starts March 1--. I saw a resort in Hollister which is a little south of Branson on the II web page, which looked to be on the water. I think Emerald Pointe is close also and may have a marina.
Good luck. It sure is fun to think of boating when it's 27 degrees outside...those HOT 98 degree days, popping a cold beer...just a few more months...