Bunk bed for twins...

Lisabet
So we decided we're getting a bunk bed for our five year old twin boys :) 
We can't decide who is going to sleep on the top, because they will fight for it.
My fiancé was thinking that we put a blanket on the bottom to make a "fort" so that way the bottom is just as fun as the top.
Help us decide! 
Thank you!! :)