I've found the best thing to do with Butts, if not eating right off the grill, is to store them whole, reheat when ready in oven at 250 - 300 wrapped in foil for ~2 to 3 hrs, then pull right before eating. If you know you will be reheating, you may want to pull them off a little early so they don't fall apart on you.
Depending on how long you will be storing, I follow these guidelines.
Let the butts cool, you don't want to get too much condensation when wrapped.
Less then a week, wrap in foil and refrigerate.
More than a week but less than a month, wrap in foil and freeze.
Longer than this (and since I have a vacuum sealer, my choice for any time more than a week) is to vacuum seal and freeze. Then defrost in frig, wrap in foil and into the oven or back on the grill.
These come out just as good as fresh and my wife actually prefers them over fresh. Which reminds me, I'm down to one butt in the freezer. Need to start looking for a sale......