Which hotel in San Antonio?

I a going on a four night trip, to San Antonio in April and was wondering what Hilton/Doubletree properties you would recommend. I am looking at staying at either the airport or the River-walk area.

I am a gold and for the money was closely considering the Doubletree at the airport or downtown or the Hilton Airport, for the executive lounge.

Suggestions for $100-140 range?