I taught at UGA for seven years and spend a month each summer in the mountains of Western Carolina.
The first thing to note about this area of the South is that it is not BBQ country. In general in the mountains (including Asheville) you should look for pan-fried brook trout, and once you get down to North Georgia look for "meat-and-three" restaurants (the meat is usually pork chop, meatloaf, fried chicken (pan-fried if you are lucky) and the three are three sides that you get with your meal (mac'and'cheesse, collards, apple sauce, turnip greens, mashed potatoes, etc.).
Salsa is a "Mexican" restaurant, but is more counter-cultural. It is IMHO GFA (Good for Asheville), but won't compare with a Chicago Mexican restaurant, although when I last visited it was pleasantly funky. I tend not to pack a lunch when I go to Asheville, but if you are in the area of the Biltmore House, you might try the Biltmore Dairy Barn. Average food, but excellent milk shakes.
One mountain place that I will suggest is the Jarrett House in Dillsboro, NC. There are also a lot of upscale dining places in Cashiers or Highlands. If you are driving through Brevard and want fast food, try either the Cardinal Drive-In or Henry's, both on Highway 64.
Athens is a college town, and as a result there will be a range of restaurants. I left in '97 and so don't know the changes in the dining scene. East-West Bistro was one of the better upscale places when I left. The Grit (on the west side of downtown) and Bluebird (on the east side) are old "hippie" quasi-vegetarian places (Bluebird has "Indian" (subcontinent) dishes.. Both are OK.
I also recommend Weaver D's (Automatic for the People) as a meat-and-three. A second excellent choice is Wilson's Soul Food. Another good one was the Planation Buffet. Weaver D's and Wilson's are black-owned; I believe the Plantation is white-owned, and the preparations will differ somewhat as will the ambience. But ask around for what your hosts recommend.
East-West Bistro
351 E. Broad St., Athens, Georgia
706-546-4240
Bluebird Café
493 E. Clayton St., Athens
706-549-3663
The Grit
199 Prince Ave., Athens
706-543-6592
Plantation Buffet
1119 Martin Luther King Jr. Parkway
(706) 353-3663
Weaver D's Delicious Fine Food
1016 E. Broad St.
(706) 353-7797
Wilson's Soul Food
351 N. Hull St.
(706) 353-7289
The Jarrett House
Dillsboro, NC 28725
828-586-0265
Cardinal Drive-In
7328 South Broad Street
Brevard, NC 28712
(828) 884-7085
Henry's
307 North Broad Street
Brevard, NC 28712
(828) 884-8658
I was unable to find an address for the Biltmore Dairy Barn, perhaps the name is wrong or perhaps it is closed. Or perhaps it is just not listed.