Lots of snacks, a few basic toiletries, diapers if we still need them, possible changes of clothes and/or bathing suits. My own kindle and/or book. PJs if it's a long flight in the evening or we're landing after bedtime.
Each kid has their own bag w/ entertainment items.
When we go we are also packing all our swim stuff bc we will arrive before check in so plan to swim all day so sunscreen and swim diapers if you need the.
Also a change of clothes for dinner if room isn't ready before you need to leave for dinner
Basic toiletries too like a brush tooth brush elastics contact stuff sunglasses makeup hair products
Since I fly from the west coast I never get in early enough to actually do anything by the time I get to the hotel. If I book a dinner reservation I go with casual so I can wear what I put on that morning.