I may have a grilled cheese sandwich for lunch.
I don't add mustard. Ketchup would be unpalatable for me. As for H&P sauce, well, I have no idea what that tastes like, so, nope. Not gonna do it.
I like my grilled cheese plain and redolent with butter. I soften the butter in the microwave, smear one side of one piece of bread first. The slices of cheese are lying on top of the other slice of bread. Then I toss the sandwich buttered side down onto a hot skillet. At that point, I butter the side that's on top. And in a few moments, it's ready to turn.
And soon it's done. Oh why am I not hungry for lunch right now!!!
Now as for cheeses, I have to admit that a sharp or medium cheddar or even American cheese (not cheese-food, though) work best for me. I have a hard time with cheese that melts and gets stringy like mozzarella or even swiss.
Grilled cheese is excellent when accompanied by a lovely tomato soup. Campbells is okay, traditional comfort fare, but the Pacific brand--found in Wild Oats or Whole Foods--now that is ambrosia!
Unless you make your own exquisite tomato soup.
Or chili. That'd be good. Kosher dill pickles on the side.
My mouth is watering.