After having 3 c-sections and having to spend 4 days each time in the hospital, here's what I'd pack if I were to do it again:
your own pillow
shoes for the shower
camera and cell phone (make sure you know the phone #s of anyone you might want to call right away- my husband forgot one of his sister's phone #s and we had to wait a bit to call her until we got the #

)
nightgown, socks and slippers
toiletries, especially cream - I was always very itchy after an epidural and cream and along with some benadryl from the hospital seemed to help
clothes for the baby to go home in
clothes for you to go home in
$ for your husband to go the cafteria
snacks for yourself after delivery
change of clothes for your husband- you might be there awhile
The hospital supplied all the unpleasant stuff like thick sanitary pads and disposable undies, as well as an endless supply of diapers and formula for the baby. The hospital also supplied towels and toiletries, but sometimes you just like having the comforts of home with you.
Good luck with your delivery and congratulations!