If you have time to do some research and learn how to work the system, then I highly recommend going to www.biddingfortravel.com and then bidding on Priceline.com. Only do this if you will not change plans because you cannot get a refund.
When we went to San Antonio, I got three nights at one of the Marriotts near the Riverwalk for $60/night. It was a very nice hotel.
BFT will help you find out what hotels normally show up on Priceline for each zone. I always bid for 3 or 4 star hotels (never lower because I've only had bad experiences with lower star hotels going through Priceline). You go to the Website for every hotel in the list on BFT and find out what their rate is for the time you plan to go. Make a chart so you can keep track.
People post what hotels and rates they got on the BFT message board so you can stay at the same rate or go lower when you bid.
This is something you do 1-3 weeks before your trip when hotels start releasing blocks of unreserved rooms to places like Priceline, so if you think you want to do this, you might book a back-up and then cancel it if you get a good 4* for less.
I've stayed in 4* hotels in Seattle, Vancouver, Washington, DC, Austin, California and San Antonio by using BFT to help me bid on Priceline and I've been very happy with all my hotels.
Hope this helps.
S.