South Padre Island is at the far southern tip of Texas. It is a barrier island, and as such is simply a large stripe of sand separated from the mainland by an aquamarine blue bay. I probably would not have chosen to go there except that a friend was getting married there and my husband was the preacher! We brought our 2-year-old and a nanny/friend and we had a fantastic six days.
This is the best "mainland" beach experience I've ever had. You just can't put islands in the same catagory as far as I'm concerned. The area is relatively new, but well developed with a civilized resort area, lots of beachy shopping, and more restaurants than you could ever try. These range from the chains like Denny's and Dairy Queen to the local flavored seafood places that overlook and overhang the water. Prices range widely, too. If you love shrimp, you'll love South Padre.
The beach goes on and on and on. It is wide and clean and the water is warmer than I would have believed. The sand is fine and white, but still hot in the August sun. . .don't forget the flip-flops!