Renny and Hornets Nest are must plays. If you like a challenge then you'll definitely want to play Renny Gold and Charlotte's Web at the Nest. That's not meant to take anything away from the original layouts as they are certainly challenging in their own right.
If you should play Renny, you might want to try to meet up with a local to be a guide. Navigation can be confusing for the uninitiated. You can take a map as a reference but the maps are outdated and at least three of the holes no longer exist (Renny Black/Original).
I suggest taking a map of Hornets Nest too. Some holes can be easily missed on the Web layout (like hole #3).
Nevin, IMO, is even more difficult than Renny and Hornets Nest. It's an incredible course that can be absolutely brutal.
Elon Long is certainly demanding. That's a favorite among quite a few people.
As for disc shops, check out
Alpine Ski Center. They have a large selection of Innova and Discraft. They also have Gateway but most of the inventory is pretty much centered on putters. At least that was the case when I was last there but I admit it's been about nine months since I was last there. Duffy Smith is the store manager, a real nice guy. Alpine Ski Center sponsors one of the leagues here in Charlotte so I tend to encourage people support them.
There's also
Infinity's End. I've never been there so I don't know what kind of selection they have.
Lastly, if you should find yourself wandering down to Rock Hill, SC for some reason, there's a shop right next to #1 tee on the Winthrop course. In their stock you'll find Innnova, Innova, Innova and oh yeah Innova. If you're a Innova thrower, you should be quite happy here. I don't know about their hours of operation though. I've only been this shop during the USDGC.
I'd love to meet up with you but I won't be available Saturday afternoon or Sunday. SmoothSailor, from Ohio is in town. I think he's here all weekend. Of course, you may want to hit up chain-addicted, a local guide for several courses here in the QC.
Have a safe trip and have fun down here. I'll be interested to read about you're experiences down here.