My family and I have been using the marina on Lake Travis for the second season now - we are very happy. I recommend you look at the
website, it is Sandy Creek Yacht Club. It really has everything you need: covered slots of different sizes, water, electricity, Wi-Fi. We moored our boat in the yacht slip and it was comfortable - clean, safe and the staff was super friendly. Plus there was a fuel station and a store with small things like sunscreen, drinks, etc. The best thing is the atmosphere. Regular renters socialize with each other, there are events. There is even a shower and a closed area for members only.