LOVE Kiawah! We always rent directly through the resort. We have always been pleased with our choices and the price. In winter we like to rent as close to the entrance as possible, but in the summer we love the turtle beach area. I like that they have 3 levels of accommodations. So east beach for summer puts you in the middle of the action.
We went through the resort as we like to do tons of the activities, so having nature preserve access is a plus for us. Oh and I suggest renting a beach setup. It's 2chairs and an umbrella set up for you on the beach every day.