If you are in San Antonio you have to see the Alamo if you have never been. It is always a pretty crowded tour to go on, but the building is worth the visit. Of course the locals have all seen it and you most likely will look like a tourist snapping photos around every corner of the grounds. But hey, if you are there you might as well check it out. The guides are very informative, but I might suggest just exploring it on your own. If I ever do go back I defiantly will explore solo.
P.S. the hotel I linked is in a great location! Right next to the River walk and all the great restaurants.