I recommend the downtown Hilton.  Walking distance to 6th St. area for after parties; and the shuttle usually comes within l blk. of it.  Reserve now and you'll get a decent rate.  Best concierge in America:  Tarik Carter.   Great pool and health club where you're sure to hang with some bands...within two miles of venue for ACL (can't remember  the name of the park, but I think it's Rilker...).