I make the cake version quite a bit, but haven't tried the muffins - neat idea!
Something I like to do with the cake that's a little different is when I cook the butter and brown sugar over heat, I add chopped pecans. I'm guessing that you can put your pineapple slice down first in the muffin tin, put a half-cherry in the center of the ring, followed by the brown sugar/butter mix, then follow with your batter. The one I do (which I can't remember the recipe exactly, and I'm too lazy to go downstairs...) uses the pineapple juice from the can as one of the liquids in the cake. If you need more help, I can check out my recipe book later on.