I just stayed at the San Antonio Hyatt this weekend. They are renovating the rooms (advertised as being completed by next month). I had one of the renovated rooms, and it is very nice. It is done in the Hyatt "modern" style with sleek furniture and a very comfortable bed. I really like how they have removed the bedspreads (eg germ depositories), and instead just have down comforters with a decorative fabric strip. The bath is very nice, large oval tub with a curved shower rod. It is similar to Westin's heavenly bed and heavenly bath.
I haven't stayed at the Hilton, but because the Hyatt is newly renovated, its rooms are probably nicer.