I grew up on a thin spreading of mayo on one slice, peanut butter on the other slice and sliced banana in the middle. Incredible. The mayo cuts the sweetness of the banana. My kids loved them.
My mom also would spread peanut butter thinly on raw cabbage leaves and roll them up, slice as pinwheels and serve with a toothpick as hors d'oeuvres at parties. Again, my kiddos loved them. It makes a great afternoon pick me up.