Dive Trip Planning 101
Step 1 - Decide on what your objective - I want to see....
Step 2 - Determine where you can see or do that...
Step 3 - Determine when is the best time to see it (Migration times, weather windows etc).
Step 4 - Determine the budget for the trip and then narrow your choices in step 2, or re-evaluate step 2.
Step 5 - Evaluate the skills, training and equipment required to accomplish your objective.
Step 6 - Passports and visa, and are they required? Does the destination require medical clearances to dive etc.
Step 7 - Make reservations for place to stay, dive boat etc.
Step 8 - Execute, rinse and repeat.
For someone in college, a Step 6A is often recommended. Determine best approach and story for the parental units and ask for funding.
Seriously, as others have said, you need to refine what your objective is. Do you want to dive for fossils, babes, manatees etc. From there where to go will be come simpler to select. Do you plan to party hard? Party hard and intoxication do not mix well with SCUBA diving. Lots of good diving in NC I am told. Ship wrecks in water well within recreational diving range. Lots of combat lost vessels, American, German, Confederate, Union etc.
Charleston SC is an easy and shorter drive from Knoxville.
http://www.scubadiving.com/travel/south-carolina-charleston Dive for fossilized sharks teeth, or perhaps one of the several wrecks there in 60 feet or less (note, wrecks in shallow water will get beat up more than deeper wrecks so don't be disappointed if they are badly decomposed). NOTE DO NOT ENTER A WRECK OR CAVE OR CAVERN without TRAINING FIRST. EVEN A FEW FEET can result in TRAGEDY! Many a non-cave or wreck diver has entered caves and wrecks crystal clear water and figured "what's the harm if I just go in a few feet" Then when they turn to come back out, they have stirred up the silt and can't find the exit. With limited air, that does not always end well.
Florida
Florida Dive Atlas | Scuba Diving Breaks it down by various areas. Have fun.