Austin, TX is my very favorite city in the US. I lived there for 5 years and I miss it every day. I've been very strongly trying to convince my DF that we should relocate back home!
Make sure you have a rental car or a bike reserved because your hotel is not walking distance to the venue. It's also tough to get taxis reliably around Austin so be sure to line up transportation. Actually the venue is pretty close to the W hotel on 2d so you can probably snag one there but I would not rely on taxis to get around Austin.
South Congress is the best area for walking around and boutique shopping. It's just south of downtown, between downtown and where you're staying. Definitely go for drinks at the Hotel San Jose - you can take your drinks out to the pool, it's super relaxing. If you are there on a Thursday night you should check out the Continental Gallery to see if there's anything happening. It's upstairs from the Continental Club which is one of the most iconic music clubs in town, it's an art gallery and shows there are usually free.
Austin Music Hall is right downtown near all the cuteness on 2d street which is where you'll find the most upscale shopping downtown. LV and all the other truly high end stuff is NW at the Domain (it's a drive, not a walk). 4th Street is the Warehouse district where you'll find a lot of music and clubs and West 6th St you'll find lower key patio type places for food and drink. 6th St west of Congress is the crazy 6th St where they shut down the streets with barricades. But I do have to say people watching from the roof of Maggie May's is definitely worthwhile if you want to venture to Dirty Sixth. East 6th is really where Austin is happening though - you should go check out East Side Kings. It's a food trailer operated by one of the Top Chef winners and the food is amazing. It's also near the White Horse Tavern which is a lot of fun.
Oh and the Hula Hut is a great spot for boat drinks. There's also a great coffee shop called Mozart's in the same general area if you're in the mood for coffee. Both with huge patios right on Lake Austin.
Hope that helps! Enjoy Austin & keep it weird