Have you gone to "free stuff to do" in... just enter in your city and lots of stuff will pop up.
Lots of times you can check the tourism board for each city or state. There will be listing of things they have going on such as Arts and Crafts, Free music and concerts.
Cades Cove is so beautiful, and I think it is a free drive, if not I think its per car.. Take a picnic lunch they have a really nice area for picnicking.
They are also a lot of waterfalls to see, you could spend a day touring them, again bring a picnic lunch.
We love to go tubing, The last couple of years we used River Rats.. They had an option for all day, I think it was like 25.00 person which I think is a good deal for all day. They had both types of tubes they regular and ones with a bottom, and life vest for the little ones. The water was cool and its a really nice float. They also had a really nice restroom, changing area, and a BBQ & ice cream stand on site, but again you could bring a picnic.
For picnicking you should check out Groupon for deals, Check for coupons in the local flyers, for buy one get one. Subway is another good option. Some of the mom and pop place's will have really great lunch specials. There is a KFC on a back side road, we got a bucket of chicken and sides for a picnic one day.
If you are going to splurge I would do it on the Apple Barn -- YUMMY -
You could drive over the mountain into Cherokee NC, and spend the day there, also The Biltmore is about a 2 hour drive ( I think) Well worth it, it was one of the highlights of our trip last year.
Check out
AAA for deals on tickets and such.
Check out Food Network, Diners, Drive Inns and Dives, for the area your going to be in, They have a listing of any place that Guy has visited. We try to hit one place where he has been when we are traveling.
Have a great time.