The Red River is on my list of places to fish. I've love to spend a week up there tangling with those monster channel cats. I've caught a couple of channels pushing 20lbs out of a farm pond, lots of others 10lbs and under. Now that pond isn't worth a crap. The owner INSISTS that everything is catch and release, I've no problems with that, but the bluegills have exploded and taken over. Found a lot of cats floating bellyside up last year, along with some good bass.
I've fished Santee Cooper a couple times, and it's a great place. I fought a HOG of a blue for over an hour before it broke me off. It ws actually caught the next day at the camp next to mine, and it still had my hook in it. 80lbs. Wish I'd have landed it. We've caught tons of fish up to 28lbs though. I also fished the Great Pee Dee river in South Carolina this past summer, caught an 18lb blue, my father caught a 24lb flathead, but nothing monsterous.
Oddly enough, I literally live minutes from the Ohio River, but I've never fished it. My boat project got stalled due to the slow economy (I own a retail snack/chip route), and I've just not been able to get much time to fish this year. I'm going to have to hook up with some guys I know from another forum and hit the river, that way, when I get the boat back, I'll have an inkling of what to expect on the river.
My top list of catfish havens to fish:
James River in VA.
Cape Fear in NC.
Red River in ND/Canada.
Plus anywhere else there's good action with big fish.