I agree with Maytrix on suggesting looking in to a sail cat. The trampolines up front are a great place to hang out while sailing, especially for teens. There will be plenty of room for your family of 5 on a similar sized sailing cat.

A lot will be closed in August, but you will still be able to find nice/fun places to eat each evening. You will need to do a bit more planning ahead, making dinner reservations by 2 or 3 each afternoon is a good way to make sure that there is a place open for you and your family to eat. We have been at many a place in the quiet season that was more than happy to stay open for just the two of us. You just have to let them know you are coming and may need to eat more like 6pm rather than 9pm.