I think the hottest I've ever been in my life was in College Station in September for a Texas A&M football game. College Station is hot and there is not a lot to do right there, but Houston is close enough that you can take a short drive to places to fill your down time. Having been to ASA/USA in other places, going to say that you will see much better competition there than TCS Myrtle and also probably way more college coaches if you are worried about recruiting aspects. When we last did ASA/USA, we had schools like Oregon, Florida, Oklahoma, etc at our games. No they did not offer any of our girls but it was really cool for the girls, Oklahoma had just won the World Series that year and then weeks later were watching us play, pretty sweet
I'd go with the ASA/USA on just about every factor except the location/beach. Anyway, I believe the schedules are already out for TCS Myrtle so maybe the decision has been made for you (unless you are on that schedule & considering pulling out).