Tubing Nantahala Falls
In Nantahala Gorge in North Carolina lies the Nantahala river and on it rests the wonderful Nantahala Falls. This rapid is a Class III and can be safely tubed down. I would highly recomend rafting down it if you are a first timer.
The Metro Chattahoochee
In Atlanta, Georgia lies the metro stretch of the Chattahoochee River. This stretch contains some mild rapids, nothing that exceeds a class I-II. There's litle to worry about until you get the 75 bridge which marks the beginning of the end. All in all, great section to relax on and have a cold one.