Seems like, broadly speaking, a very East coasty sort of thing. Not that we don't have great respect for them out in the midwest but sandwiches are elevated to an art form out east. Here, the predominant indigeonous sandwich is BBQ brisket, on really really cheap white bread, the sort that gets immediately soggy from brisket juices and BBQ sauce so that you have to eat it with a fork. Still, its a masterwork, but that's more about the meat than the sandwich itself.
I like grilling steak, onions, and peppers over charcoal and then slicing it all up into a sandwich with cheese. Weird variant of the pepper steak. And I smoke my own pastrami, which now paired with my meat slicer, makes great pastrami-on-rye, cold or hot.
But sometimes I like to go a bit further back in the realm of sandwich-making...thinly sliced cucumber on crustless buttered bread with a bit of coarse salt and pepper, hard to go wrong with that. Simple, light, and fresh.