I'm all grows up, and nothing makes me feel more so than renting a car. (Except perhaps the fact that some of my friends have started having children on purpose.)
In Charlotte, Hertz seems like a good bet, if only because I'll never use Avis again.
The folks behind the counter don't move too quickly and they are very confused if you aren't in town for NASCAR, but they're nice enough and they don't give you the hard sell on insurance and upgrades. The shuttle is quick to and from the airport, and the prices are dirt cheap if you're used to renting cars in NYC.
Nothing about the experience blew me away, but I'd do it again.