The Lynx Blue Line mentioned above (Charlotte's light rail system) should be sufficient for you to get around Charlotte, especially if you stay at a hotel in uptown. Below is a link to everything you need to know about Lynx (you can get on the line in uptown at 3rd street, 7th street or at the main hub on E Trade Street):
Charlotte's Lynx Train Guide | LYNXcharlotte.com
Depending on what you want to do, you may find you don't even need to leave uptown as there's tons of bars, clubs and restaurants right there (Ri Ra's, the Irish pub mentioned above, is one of my favorites). I highly recommend Howl at the Moon at the EpiCentre if you like a dueling piano bar. Also, I stayed at the Marriott in uptown this weekend and they gave us a complimentary breakfast (with really great food) plus free passes to three bars for that night.
If you're looking for more cultural types of things to do in Charlotte, there's always some sort of play or symphony performance or art gallery (i.e. Bechtler Museum is mentioned above). The site below usually has a pretty good list of Charlotte events happening every weekend:
Charlotte NC events - concerts, theater, festivals, free events & kids events
Enjoy your time here!