Charger, Duluth is nice but is quite different than Tennessee. I moved to Minnesota about 4 years ago from Alabama. There is a huge variety for a fly fisherman in this state. If you and your wife share rods you already have the right rods for most situations. I use a 3wt for the mid size to small (trout)streams, a 4wt for lakes and middle to larger(trout) rivers, and 8wts for anadromous rivers. Im not big into warm water fly fishing but a 5 or 6wt should do you fine unless you chasing huge northerns or muskies, in that case i would probably go with a 10wt.
The state is beautiful and as you get to know it you will find out it has alot of diversity. Hows the fishing on the watauga and south holston? I've never fished those two rivers but i have always wanted too. I spent half a week last June fishing the stream of the smokies in the GSMNP. Sure do miss those Tennessee mountains.
Daniel