Agree that Memphis is a little sketchy. Downtown especially.
Tourists and police mixed with a lot of homeless folks. I would skip it in favor of a smaller town down the road.
If you stop for in Memphis, these were the best spots I found.
Central BBQ
The place to go, but the food in downtown has gone downhill.
Not nearly as good as Kansas City or Texas
Blue Plate Cafe
Good breakfast, not great
Large portions
Jackson is more relaxed and feels safer. Not sure it’s worth adding 30 miles to your trip though.
If you stop in Amarillo, visiting the stock yards is pretty fun. The Stockyard Cafe has good breakfast and you can walk upstairs to watch the stock auctions. I liked listening to the auctioneer, but couldn’t understand much of what he said.
Good restaurants are:
The Coyote Bluff Cafe - small hole in the wall place. Go on off hours to avoid the line. Burgers are juicy and big. If you like spicy, try the Burger from Hell.
It’s a Punjabi Affair - good Indian food.
The Big Texan Steak Ranch & Brewery has a 72 oz. steak that’s free if you eat it all in one sitting. It’s huge. Expect food coma to follow.