I don't bring much (in fact, for my second I had nothing b/c he was preterm and I was not expecting to deliver... I had to send DH to The Gap down the street to get undies and PJs). I have really fast labors so I don't bring anything to cover that time period. After the kids were born, I changed into my own PJs or comfy clothes as soon as possible. I guess I will bring my toiletry items, PJ bottoms, several pairs of undies, a nursing bra, a couple of t-shirts or tank tops, a pair of comfy pants (elastic waist or similar), a hoodie or cardigan (to throw on if I get cold), socks and a pair of flip flops. Of course, don't forget your camera and a cute "going home" outfit for your little one! I might have missed something... but I think that covers most of the essentials.
Thought of a few more things: You might want your cell phone charger and/or charger for your camera battery... and a baby name book if you are still up in the air on a name.
Oh, and in response to your specific questions, I have never brought food or a cooler. And I don't wear nightgowns, but I like to have PJ bottoms with a tank or tshirt on top.