We stayed here for 4 nights with our 2 kids (ages 6 and 8) in two adjoining rooms. Very nice greeting when you arrive (with fresh flower leis for the girls and kukui nut necklaces for the guys, cold towels and fresh juice) but check-in was slow. We were able to check in early which was appreciated. Love the location as you are slightly set back from the craziness of Kalakaua Avenue (hotel grounds set in behind the Royal Hawaiian shopping centre).
We had a room in the older section (no lanai but windows open). Rooms are thoroughly modern with mini-fridges, high ceilings and beautiful amenities. Note there is a mandatory "resort fee" which includes wi-fi, self-parking and discounted kids meals (we did not eat at the hotel). Because we had two adjoining rooms we had to pay a $25 connection fee each night as well as the resort fee for both rooms which I found annoying as one room was for the children (no self-parking necessary!).
One of the highlights of our stay was taking the tour of the hotel with Thelma, Director of Cultural Services. We learned so much about the history of the "pink palace", the area and the islands. Thelma was a wonderful guide.
The fitness centre, located in the lower lobby, had the usual equipment (treadmill, elliptical, bike, weights) all in working order. The pool itself is small but you have access to the Sheraton next door which has a kids pool with waterslide and two hot tubs (which kids can also use). The hot tub at the Royal Hawaiian is only for adults.
I found the beach attendants to be extremely friendly and helpful - shout out to "T"! We did an outrigger canoe ride (which we purchased from them and charged to the room). It was slightly pricier than other companies further down the beach but they supplied the extra paddlers (as were only 4) and included pictures in the price ($25 pp).
We had drinks one afternoon at the famous Mai Tai Bar which was very enjoyable. Did not eat other meals at the hotel as the hotel is within walking distance of many (more reasonably-priced) options.
Overall a wonderful stay in a historic charming hotel.