Toiletries and Medical Supplies: Never, never, but never forget some anti-diarrhea medicine.
Even if you don't drink tap water and only drink bottled water; even if you wash your teeth with bottled water; even if you don't use ice... you still have a good chance of getting diarrhea!!!! Believe me, I know....
So don't take any chances. It can ruin your holidays!!!!
Clothing/Shoes/Weather Gear: The main thing not to forget are... sunglasses and a hat
Toiletries and Medical Supplies: you may have some stomach problems with fresh fruit and/or water so don't forget to bring something for it