Well, I can't say much about...
Favorite thing: Well, I can't say much about the town of Sonora. It's just your average Texan town. However, about 15 minutes away lie one of the greatest treasures of North America: the amazing Caverns of Sonora. Since you made it this far, don't leave town without seeing them. There are 3 types of tours, but the one I reccomend it the longer of the normal tours (the Crystal tour) which costs about $20 and takes about 2 hours.
Before the texan hills...
Favorite thing: Sonara, when heading eastwards, is one of the last large cities on the I-10 before San Antonio. I've often had problems finding a place to sleep when driving through Texas late at night. Sonara has about 6 hotels to choose from making an ideal late night stop.