Great area to visit the Confederate Air Museum, and the Texas Air Museum.
Short driving distance to South Padre Island and Port Isabel, both of which are great places to visit.
Quick Tips:
Drive to the Mexico border, leave car at border and take walking tour of Mexico.
Best Way To Get Around:
I found it easier to get a map of the area and drive to most of the places I wanted to go, except Mexico - would suggest using public transportation to go over the border.