Any Disney restaurant has plenty of kids in it (other than V&A), so you're fine and at those ages. And, on average, they should have no issue with sitting through a signature meal which normally take a little bit longer than a 1 TS meal. If there are special considerations for your family where being able to sit through a meal are a factor, then you may want to reconsider, but only you know your family and what they can handle. Food wise, there is a children's menu that should satisfy most picker eaters, if that is a concern. My now 10 year old has been a steak lover for a couple of years now so we always have a steakhouse or two in our dining plans for Disney.