Potbelly's is SO good. Unfortunately not great for you. But, if you make some substitutions it's not that bad. They have an awesome nutritional calculator on their Web site:
Steer clear of the side dishes (I think the tiny thing of macaroni salad has as many calories as a sandwhich!) and get yourself one of the "Skinnys" which is a sandwich on slightly thinner bread. I believe the mushroom melt has about 300 calories - it's my fav!
You get to pick your toppings similar to subway, so you can opt out of mayo to save on calories there. I like to add mustard, hot peppers, tomatoe and onions. The onions are chopped finely so they aren't too strong.
They also have a nice assortment of diet drinks in the cooler - things like diet Stewarts sodas and IBC rootbeer. At least at the ones by me.
multigrain wheat bread is probably not whole grain. That's one of those sneaky marketing names. Unless it says whole grain and whole wheat you can't trust it. Sorry