For lunch Friday or Saturday, Ridgewood BBQ in Bluff City. Pork sandwich. Baked Beans. If you like blue cheese, try their blue cheese appetizer. I also like there (not-mayo) slaw and home made fries.
Peerless Steakhouse is a successful local institution just off I-26 in Johnson City.
For a quick bite (and a chili bun) try any of the Pal's drive ins. Really ugly and distinctive building. (Think odd shade of blue green with a big hot dog on the roof).
If the weather is beautiful, and if you have the time, drive on down to Asheville NC on I-26 which may be the best interstate road to go through any eastern mountains. Lots of choices in Ashville. We tend to eat Marco's Pizza on Merriman Avenue there; but you come from the land of good to great pizza, so it might not be right for you. On the south side of Asheville, Tupelo Honey Cafe gave us a very good lunch several weeks ago.