By the time you get to Hawaii, the best place to see whales will be off the coast of Mauii
and you can quite often see them from land . Take a snorkel tour out to Molikini and you will likely see (and stop for) whales. If a whale excursion is offered I'm sure you will see whales.
There is only one place to go to see an ACTIVE volacano and that is the Big island (Hawaii). The best way to see activity would be to take a helicopter tour when you are in HILO.
Celebrity food is usually as good or better than the other popularly priced lines and dining service is generally superb.
Celebrity entertainment is generally excellent.
Your ship is modern, beautiful and well equipped in every aspect.
Weather in Hawaii will vary a bit from island to island and will generally reach 80 degrees f in the daytime.
Enjoy your cruise.