Here are some suggestions:
At the put in for the Tuck, right at the Dillsboro Bridge, there's a little stream that feeds into the Tuck. Just above the confluence, there's a nice little pourover and pool where you can practice your strokes and maybe rolls, too. It's a little shallow right at the pourover, so if you want to roll, move away a few feet, into the middle of the pool.
The river itself should be way too low to paddle down, unless you like crab-walking and scratching the heck out of your new boats. Not a fun idea. Plus, there's no shuttle anyway.
Another idea is on the Tuck right in downtown Bryson City. There's a little park down near the railroad depot. You cross a hanging bridge, walk through the park and you are right at a nice section of the Tuck where (again) you can practice your rolls, peel-outs and eddy turns. And for a little excitement, you can paddle upstream about 25 yards and there is a small hole to play in or around.
To help your wife gain her roll, get out of your boat and stand in shallow water at the stern of her boat. When she flips, grab the stern of her boat with a cross-grip, meaning your left arm goes across the "top" which is really the hull of her boat, and your right arm goes across the "underside" which is actually the deck of her boat. Then, as she rolls, you assist her by forcefully uncrossing your grip, to make sure she is successful. This removes the "doubt factor" in her mind while she's underwater, enabling her to concentrate on the task at hand and have fun. If she never again fails to roll, with your assistance, sooner or later she will start rolling with no assistance from you.
Finally, if you can stand the frigid water, Surfing Wave on the Nantahala is a great place to practice. You peel out at the top of the wave train on river right (surfers left) paddle through the wave train and eddy out on river left at the bottom of the wave train. Then go ahead and ferry over to river right, paddle up in the big eddy in front of the beach and do it again.
Glad you got connected to Juliet at ERA.