Penny, I can't promise you water at 85° but it won't be as cool as you might think--especially in Mazatlan and Puerto Vallarta. Cabo San Lucas, being right on the tip of Baja California, can catch some of the cool currents coming South from Alaska; but by the time it gets to the other ports it has mingled with the warm Northward currents and is pretty nice. And it will be warm and humid enough that the water will feel pretty darn good.
Sapphire Princess is enough like the other ships that you will feel right at home; but it also seems somehow more spacious. For one thing, the Promenade Deck is much wider; and the whole ship seems to have a more open and airy feel. I just love her.