I know I'm too late for you, but the best food isn't at the Riverwalk or Mercado, but unknown little places in strip malls. That applies to virtually every town in the US these days. That said, you cannot miss the River Walk, period. I've travelled just about all of the United States, so trust me when I say it is one of our great treasures. We decided that a barbecue place was the best food there. If you are a bar fly (I am, decidedly) there is a bar in an old hotel near the Alamo, where Teddy Roosevelt drafted many of his Rough-Riders. I love historic old hotels. The Alamo is only a disappointment if you don't like real history, just like the Disney version. People tend to not know that the Alamo is just an old church, a little place like many other old Spanish mission churches. To me it doesn't subtract from it, it adds to it. I love the old mission roads and churches. If you are into this kind of stuff, there is a map available that connects all of the old mission churches in the area ... they are so close (yes, including the Alamo) that you can drive it in an hour or so, and could hike it a day.