Also will probably try to do some shoreline/pier/non-boat fishing while we're there too so any recommendations on places and techniques for that would be very welcome.
I love fishing the surf on South Padra, you can catch a lot of fish. You will mainly catch whitings (see below) and they are real good and fun to catch, and you can do it when right there with the family the kids play on the beach:
http://www.texasgulfcoastfishing.com/whiting.htmJust get your self a surf rode and dead shrimp, 2 or 3 hooks, and I use one those claw sinkers kinda like the pic below
That keep it out there and holds good in the sand. You can buy all of this while you are down that at Wal-mart for cheap. Just cast out passed the second sand bar. Go to the 3rd sand bar and you will catch all kinds of stuf, Sea Ray, sharks (good eating). Good luck, have fun.