Sorry, but not even Settebello's true Neapolitan masterpieces are worth an 80-mile roundtrip detour. Access to downtown SLC is relatively painless from I-80 and totally on the route... Should the OP wind up in town, a visit to Les Madeleines for out-of-this-universe baked treats for the road would be well-advised.
Absolute don't miss in Reno, NV
I miss this more than anything else from my years in Reno.
I believe it got a glowing review by Sunset Magazine some years back. Despite that, the quality stayed high.
In Truckee, Ca a fantastic breakfast can be found at Squeeze Inn. You will see where the name come from upon first view of this gem.
If you are passing through Utah on I80 your going to come close to down town Salt Lake. This gives you a lot of great dining options all pretty close together. I will suggest a few places, but it might help if you give us an idea of your budget/cuisine preferences.
Takashi: *Really* great sushi, very urban and hip.
Bambara: Located in the Hotel Monaco. "New-American" cuisine, on the upper end of pricey-ness, but one my favourite restaurants in down town SLC.
Settebello: Neapolitan style Pizza. I am not a pizza lover myself, but pretty much everyone who is raves about the place.
Spencers: Old school steakhouse. Located in the Hilton Hotel. Pretty pricey but you will be hard pushed to find a much better steak.
Baxter's American: American comfort food with their own higher-end unique twists, e.g. "Not your mothers meatloaf"
For addresses and website links see: