In general, how many things need to be booked in advance?

Booked a last min trip to Honolulu in a few days. Father son trip as my parents ain’t have money like that growing up, but now I’m an adult doing OK for myself. I got our flights, hotel (Outrigger Reef Wakiki) and I booked a car for 2 days (we are there 5 total) because based on research it isn’t necessary the whole time.

I want to do as much as we can within 5 days without overcrowding our itinerary if that makes sense. Probably no crazy hikes because he can’t walk uphill for more than 30 min probably .

In terms of restaurants, boat tours, luau, etc. should I be figuring this out before we leave? Don’t want to miss out on anything necessary because we didn’t prepare!

Thank you all