A variant on this sandwich, which happened to be a staple of my childhood, is to use peanut butter, not butter, and drizzle honey on the peanut butter before you add the banana.

I don't know how squidging the banana will go with honey and PB as I was a neat kid and sliced the banana up, but this is a tasty treat that should go well with any kid, and many adults as well. Also, if you put the honey on the bread first, it kinda crystalizes in the bread after a minute or two, so it creates one more interesting texture as you eat.

So you've got peanut butter, honey, banana, bread and the honey/bread crystalized combination. Could there be a more perfect taste in ones mouth?