I'm a bit partial to the Wasatch Front. I just moved from Utah last year. If you're in the Ogden area, go to Remuda Golf Course in Farr West. They have outstanding BBQ.
I cant believe no one has pointed them in the direction of Ye Olde Steakhouse! Great atmosphere and Great food! Highly recommend Littons as well. Todd Blackledge featured their food in one of his Taste of the Town specials!
They may be expecting good BBQ since they're traveling to the "South." But Knoxville is not a good BBQ town (not a good food town in general). If they want BBQ, tell them to avoid Calhoun's (because it's awful) and the only decent choices are Dead End and Sweet P's.
Best tavern is Suttree's.
They'll enjoy walking around downtown.