Since you have not yet set your itinerary, I would suggest you consider visiting the Vanity Fair outlets in Reading PA. Reading is about 60 miles or so north and west of the Philadelphia airport, if you are flying.
I lived in that area for a while, and there are a few other things to see: the train museum, airplane museum, and it's not far from Gettysburg.
But back to the VF outlets, you will go crazy. Bring a few extra empty suitcases. They have every imaginable style, brand, color etc. and their prices are better than anywhere else I have found. I wear the VF string bikini which retails for $6-8 in department stores who rarely have much selection of colors. I can get them there for $3 and they have every color and matching bras. In all the places I've been shopping, there is absolutely nowhere that has a comparable selection or better prices. Usually I try to buy all my underwear there, unless I am overcome by temptation and need to make an emergency trip to Victoria's Secret.

Anyway, they have not only VF, but Bali, Warners, pretty much all the major brands.
What they don't have, strangely, is hosiery by Berkshire. However, the Boscovs department store which is popular in that area, usually has a pretty good selection at prices better than you can get online. There are a few Boscovs' in Reading.
I don't like the rest of the clothes there very much though. The other shops are not that great, but it all depends what you like. A lot of people take bus trips there to do their back to school shopping, so plenty of people disagree with my opinion about that

They have a lot of inexpensive clothes, and sometimes I've found things I liked. I don't often say nice things about Reading (my ex lives there), but the VF outlet there is the best place in the world to buy underwear.