Is it really worth the effort to repack, switch hotels and unpack on a four-night trip just to check out some pools at a Hyatt?

I will dissent and say just spend the whole time at the St. Regis. I just came back from Kauai and did Waimea Canyon and Polihale Beach in a day, with plenty of time to relax in the hot tub at the St. Regis before going to dinner that night.

You're going to an island that is renowned for its natural beauty. I wouldn't let man-made pools at a hotel sway my decision.