I have lived in Kingsport all my life.
My favorite restaurants are :
Cheddars Casual Cafe - must try their spinach dip !! They have good steaks, too. Actually, I've never had a bad meal there. World class chicken sandwich is great, Key West chicken and shrimp is good, ribs are good, chicken pot pie is good, chicken strips, everything :).
Texas Roadhouse - good steak and ribs, love their cinnamon butter and fresh rolls.Must try their loaded sweet potato, it's great.
Chop House - good steak, kinda pricey.
Pratts BBQ and Bradens BBQ - good and have a variety of sauces to choose from.
Moto's japanese restaurant -- yummy and their shrimp sauce is great
Riverfront Seafood Restaurant and fish market - great seafood and you can dine on a deck overlooking the holston river. Their tartar sauce ROCKS !
Pals is a Kingsport tradition for fast food. got their start here in the 50' I think. Lots of us are addicted to their 32oz tea/peach tea/razzie tea.
Olive Garden is under construction and will open soon.
Cootie Browns is closed in Kingsport but there is one in JC.
Purple Cow ...ehhh it's fast food and I have had good and bad experiences there. They have a big selection, though.
Zaxby's - my family loves their chicken strips and fried pickles.