I'm not generally a fan of sandwiches, but I ate at Earl's two days in a row on my last trip to Vegas. Cheap, quick, and consistently good. Can't really ask for much more. My favorite has got to be the caprese, whose flavors had held up even after a 2 hour journey through an airport. My second favorite is the Hawaiian. How can you go wrong with pineapple and ham?
I wouldn't make the twenty minute drive to Disneyland for Earl's (just because I'm not too big on sandwiches), but it's always a stop when I head to Vegas.