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The lower Mississippi, between Cairo Illinois and the ICW below New Orleans is a wasteland for recreational boaters. There's not much to see--most of the land next to the river is agricultural with levees on both sides that you can't see over. And nearly all of the traffic is commercial and it's particularly busy in New Orleans, you really have to know what you're doing down there. There are only two marinas for recreational boaters below Cairo, one at Memphis and another in Greenville, Mississippi. That's it. You have to go 450 river miles between refueling facilities on that stretch and there are no docks or marinas on the river at New Orleans. Ask yourself if you must go that way.
Nearly all rec boats and Great Loopers will go up the Ohio a few miles to the Tennessee and follow it to the Tenn-Tom, and go down to the Gulf of Mexico that way. The scenery is much better, there's less commercial traffic, and most importantly an abundance of marinas and other facilities for recreational vessels. You'll need to lock through a few dams but that's something you can learn how to do on youtube.
All rivers and waterways maintained by the USACE have a minimum channel depth of 9 feet iirc. The inland waterway system is pretty extensive.