The news today was that Mayor Winn announced phase-two plans for the Austin Light Rail, which would connect directly between Mueller, downtown, and the airport. That would pretty much rule.
Having lived in San Francisco for years, Jill and I got quite used to taking light rail pretty much everywhere (I didn't even own a car for the 5 years I lived there). Having that chance in Austin, even if it's a few years away, would be awesome.