As far as Port Aransas goes we have stayed at Gulf Waters RV resort twice...it's hard to get a spot there and you need to call well in advance to reserve a spot. It's actually an owner based park and a property manager handles the reservations. Both times we have been we have been very happy. The first time we went last summer I could not get a spot there or at Pioneer and booked at Mustang Island State Park. A week before our trip I tried again and got a spot...someone canceled. I'm glad too...Mustang Island SP is a dump...I love state parks and we visit them often but the RV part of this par is pretty much a parking lot with one RV spot right next to the other. Pioneer is for sure nicer and the only other place I'd bother staying down in Port A...slots are certainly packed in tighter vs Gulf Waters but overall it's nice. We love being able to stay at a RV park that you can walk to the beach and has a swimming pool.
I searched on here and saw some older reviews of Gulf Waters and many were poor but only due to the property managers...I think in 2011 they may have gone with new management as all the staff we worked with and spot too were very nice and helpful. Our last full day there my daughter was a little sun burned and they were kind of beached out so I went into the office and asked about stuff to do and the lady working there was very helpful...she even asked the ages of our kids to be able to give age appropriate advice. We will be going back next summer and hopefully many more summers to come!
http://gulfwatersrvresorttx.com/