As I am answering you questions keep in mind that we had a 2 year old, so we did not participate in some of the things that were offered.
Catalina Island was very nice. Try to get of the ship early, to get a best spot on the beach. Bring some fresh water to drink (water bottle), they charge $3 for a bottled water. There is water and juce offered when BBQ is served. There is a band and volleyball. We only stayed for about 3 hours, we had to put our 2 year old to sleep, but undrstand there are other activities during the whole day (dancing, games). There is also a small market were you can buy local stuff and cigars. The other option is to stay on board and enjoy the pool. You will have the pool to yourself. Same sea water and no sand.
We did not go on any excursions. During our previous cruises, I schedule my own excursions.
If you want my personal opinion of San Juan, I was not to impressed with it. We walked around for about hour and a half and wend back to the ship. I talked to other people and they liked it more. I'll say get off the ship, look around and make your own oppinion.
We did not go to the Olympic. They only accept reservation for kids of 12 and up. I think the food in the main dining room was as good, but for the speciual occation and a little change it might be worth it. The charge is still $25.
The band is still Onlyx.
I think they did have a tropical party one night. They also had a TexMex party. Again being with 2 year old, we did not do much past 11 pm, but looking at the video at the end of the cruise there are quite a few people who stay past midnight and party. I am sure you will have a great time.
One think we did enjoy is a room with a balcony and having an ability to order the room service from the same Lunch and Dinner Menue as in the main dining room.
If you get a chance go to the Atlantis resort in Nassau. Pretty impressive. You can walk there or take a cab. If you walk the view from the bridge is great.
P.S. People still save space by the pool early, so if you want to get a good space by the pool, you need to be there by about 7am to save a good spot. I know it's not a good practice, but at least you will have a space by the pool.
Hope that helps.