I try to pack as little as possible, while still covering my bases:
Clothes for me (2 shirts, pair of pants, nursing bra, socks and undies)
Basic Toiletries (soap, toothpaste/brush, hairbrush, contacts stuff, glasses, shower shoes)
A couple of Depends to wear on the way home--not sure if I'll use them, but I hear they're good and more comfy than wearing a giant pad
Breast pads and lanolin
Baby's clothes + receiving blankets when we take her home in the car
Laptop--undecided on this one, since DH will be going back and forth between the hospital and home. Last time when it was our first we brought it so we could send out an email.
Snacks for labor
Massager (I tend to feel labor all in my back)
Rice bag (heating pad)
DH has his own small bag packed with a change of clothes and a toothbrush. He probably will go home to shower so that he can also see DS, but this is just in case things get messy during the labor or if there is an emergency and he needs to stay at the hospital with me and/or baby.
I also have my diaper bag packed with the normal stuff: diapers, wipes, cream, extra change of clothes, but that'll probably stay in the car.