What is the best way to reheat a sub-style sandwich? So you go to a deli, pizza place, or any number of places that will sell you a 12"+ hot sandwich (e.g. a philly cheeseteak).  You eat half and save the other half for another day.  When that other day comes, what's the best way to reheat it?

For many other foods, the most common ways are microwave, toaster oven, regular oven and skillet.  Unconventional ways I can think of would be steaming and sous vide (though the latter seems excessive for a sandwich).

The goal would be to get the sandwich hot enough to remelt any cheese, but to not render the bread too mushy or too crunchy (toast).

What method or combination of methods would you recommend to reheat a sandwich from the refrigerator?  Be sure to specify whether you'd use higher or lower temps or power.  If no one method would work well for all sandwiches, could you post guidelines?
I would suggest opening the sandwich so the filling is facing up, removing any toppings that you would prefer to remain cold, and sticking it in an oven or toaster oven for a bit. That gets the heat to the center of the sandwich immediately, though you'll want low heat (maybe 250F?) and not to heat it very long or the bread will get too toasted. It won't ever be as good as the day before, but I find that microwave reheating tends to result in poor-quality bread.