Most of the local burger stands around here in Wichita tend to the mustard, pickle (sometimes chopped as a dill relish) and onion (grilled by request) standard. Some places will actively humiliate you if you order ketchup ON your burger, and will simply point to the little packets on the counter -- not mean-spirited, they just consider ketchup something for fries and onion rings, not your burger. Some places even give you a American/Cheddar/Swiss option for your cheese.
If I'm eating a chain burger, I normally get them regular, unless I want to make sure it's fresh (less a problem than it used to be, but I had a Whopper the other day that was inedible - lettuce was COOKED, tomato had no texture, and the mayo...
). If I'm special ordering in the burger stands, I like mustard, pickle, grilled onion, mayo, and cheese. At home, all the same, with a freshly-picked slice of red tomato and a couple leaves of lettuce.
But I will sometimes dump some steak sauce, or blue cheese dressing or barbecue sauce on a pickle-and-cheeseburger for a change of pace.