There really are a lot of club options on the Charleston area, from very large to relatively small and everything in between. They all have something valuable to offer; a lot of your choice depends on what level of play and and what type of playing/training environment and club culture you and your children are looking for to fulfill your vision of an enjoyable and rewarding experience.
My advice (as you're already doing) is to reach out and get feedback from parents and players in the area who have experience with the different club cultures and experiences. I'd also recommend going to more than one tryout to get a good feel for how the players, coaches, and parents interact and what the face-to-face environment is like. While we're all going to tell you good things about our respective clubs, it's a safe bet that there is no one organization that is going to be the "perfect fit" for every single player and family's needs.
If you'd like to find out more about the club I happen to coach for, Charleston United Soccer Club, feel free to drop me a line at coachchass13@gmail.com and I'll be happy to talk to you about who we are and what we do; I hope you will get good feedback on multiple options in the area so you can make an informed choice for (and with) your children!
