I didn't bring all that much with me for DD:
comfy loose clothing, slippers, camera, boppy, toiletries, nursing bras, snacks. I may have brought my own pillow (but I honestly don't remember). This time, since I'll be delivering in February, I will also bring a robe - it will keep me warm and be easier to breast feed than wearing a sweatshirt/long sleeve shirt. Hospital food isn't great - so snacks are good for you and hubby both.
I pretty much used everything that they supplied postpartum - mesh underwear, pads, ice packs, sitz bath, towels.
Don't bring a pump (the hospital should have one available for you to use if you have to - you may want to double-check though). It's just one less thing to worry about. My milk didn't really come in for a few days, so nursing pads weren't really necessary for me either.
DH also packed a few things in my bag - toothbrush, 1 change of clothes, Tums, Tylenol. I think that he enjoyed being able to freshen up after delivery, and we packed some OTC meds just in case he needed them.