I agree with everyone else!

The 3 things I appreciated the most:
1. Giant undies (I got mine from Best & Less - they only come in light blue, light pink, beige and white - you'll know the ones I mean - and get a size bigger than you need - once a giant maternity pad is in place you will appreciate the extra room!!!)...
2. Some really nice shampoo and conditioner - the first shower post op is a wonderful experience!!!
3. Some lip balm or similar (for some reason my lips got really dry - may have been air-con/heating??)
And not sure if anyone has already mentioned it (read so many good ideas here) - but don't forget a going-home outfit for bub - gorgeous but easy to get on!!!
All the best for a fabulous and memorable birth - My C/S was a beautiful experience - I trust that yours is too!
Lily