Most wheeler bags have a hidden compartment that you probably didn’t even know existed! Open the suitcase and look for a zipper in the lining at the base of the suitcase. Inside, you will find a small space between the two rods that run up the back of the bag.
This is a perfect space for stashing documents that you don’t want to risk losing in transit, or losing them if someone opens your bag while you left that in your hotel room.
Although, of course, this is not a good spot to store currencies, credit cards or passport.