Toasted, melted, grilled, or plain?
Yes. Yes. Yes. Yes.
Brie, Blue, Monterey jack, cheddar, American, Swiss, Cotswold, havarti, provelone, feta , Mozzerella, muenster, etc.
(I have accepted cheeses as my personal savor.)
White, wheat, sourdough, rosemary & olive oil, rye, pumpernickel, pretzel, beer bread, bagels, pita, roasted garlic, onion rolls, French, biscuits, naan, etc.
Depends on the sandwich. I often add herbs like dill, black pepper, garlic powder, onion powder, parsley. Occasionally, something like olive oil, BBQ sauce, mustard or steak sauce will pop up.
Veggies like sun-dried tomatoes, sautéed mushrooms, or onions (raw or grilled) are solid options.
Tabouli works well for some combos.
There's a place near me whose BLT is toasted with
brie[/I, lettuce and tomato. No bacon.