We were in Gatlinburg/Pigeon Forge/Sevierville last October for fall break - 6 adults, 5 children ages 7 - 14. Lots of great suggestions that I would echo that have already been mentioned.
We spent one night at Wilderness at the Smokies. Kids LOVED the water park. I would not recommend the restaurants that are on site - very expensive and even though kids "eat free" adult meals are priced to make up for it. Call in an order to Pizza Hut right up the road - $10 large pizzas, slip through the drive thru and pick it up. One night was all we needed - rooms were extremely nice, we stayed in one of the suites with multiple areas to sleep and it had an extremely nice kitchen.
The rest of the time we had a great cabin - we used Eden Crest Vacation Rentals, rented a large cabin and stayed in Bear Creek Crossing. Very nice community of log cabins about 15 minutes out of Pigeon Forge. Gatlinburg Falls is also a good log cabin community. Satellite TV, hot tub, pool table etc kept kids entertained while we "relaxed".
One tip on eating - especially at the Old Mill (wonderful food) - go for lunch. We would eat early afternoon around 1 - 2 - tried to get right at the cut off to end lunch, prices were much cheaper and portions were very large. It would save my family of 5 about $20 each meal. Then we would grab a sandwich for supper or eat back in the cabin. We did Cades Cove, shopping, horseback riding and go carts. Again - go in the morning before noon, much cheaper. Look for coupons - just about every store/attraction has coupons on display at the welcome center, on display racks outside motels and restaurants, online etc... It can get extremely expensive if you don't watch it - I did a lot of screening online with the kids so they knew what was up there and knew that we wouldn't be doing everything they passed on the road.