The best marina and ramp are at the State Park, Public Beach 2. It is right off of Hwy 54 in Osage beach. They have covered boat slips that are probably less than $20 USD per night (not sure on exact cost). There is a ton of parking and the ramp is 3 lanes wide. There is also a sand beach near the ramp. The water is not crystal clear it but it's not as dark as Lake Erie. Most people have no problems swimming in it. The lake is basically a dammed river that weaves around the state for about 90 miles. There are plenty of bars and resteraunts on the waterfront. For adults there is the party cove. There are several coves that have more of a family atmosphere as well where you could tie up. The best part in my opinion is the scenery. There are multi million dollar homes, old fishing cabins and some very unique architecture.
It will be well worth the trip. If you can, schedule your trip around the Lake Area Shootout the last weekend of August. You are guaranteed to see 200 mph boats that weekend.