I won't talk about anything medical, just something silly, but I hope, useful during your hospital stay.
I can't talk about other surgery, I just talk about thyroid surgery.
It's very useful to bring plastic hair clip...I forgot mine and ended up using rubberband for my hair during bath!!
I had a kimono 'uniform'. It's not cotton, it's slipping away all the time. I wish I bring a brooch...or a safety pin to avoid wardrobe malfunction :)
With all those pipes and bandage, I wasn't able to wash my hair...so prepare yourself to have dirty bloody hair (literally speaking)
Bring disposable undies. Hospital is not a place to think about 3R :D
Bring a facial cleanser and facial cotton. I didn't have the energy to wash my face, so I cleaned it with facial lotion (mine was Ovale)