I've been hearing all sorts of great things about Austin for years and now that my favorite airline flies there (Virgin America hai!), I really have no excuse not to check it out.
My question is -- once I get downtown (or wherever it is that's the best spot for visitors to stay in), what's it like getting around? Can I walk places? Is it fairly easy to hail a cab or take the bus? Or will I need to rent a car?
Unless you plan on staying downtown the entire time, you do not want to be in Austin without a car! There's public transportation, but few locals who can actually afford a car use it. Save for the downtown, it's not a very pedestrian-friendly city. I remember being in some places where there weren't even sidewalks.
Downtown is really cool, though, if you just want to spend your trip walking around there, listening to music, eating, etc. If you want to go anywhere else, take a cab, or rent a car, and make sure it has working AC! That's another thing to factor in: the heat. You'll probably not want to walk around so much during certain times of the year.