For those who aren't aware, the Riverwalk is a "channelized" section of the San Antonio River set below street level and lined with two stories of shops and restaurants.  It is right in downtown S.A. with lots of other neat areas around it including the Alamo.  (The photos on page 1 and 2 are from a 2007 trip.)

However, a word of warning--don't go the week between Christmas and New Year's unless you just love crowds.  And I mean shoulder to shoulder crowds.