Thanks everyone! I do indeed miss the St Regis Princeville, but rooms there would probably be over $2K a night at the moment. I decided on a couple of nights on points at the Hyatt (including my girlfriend's birthday) and then three nights at ~$500 a night at the Westin before we head off to a quieter island (Molokai).
For those who have never been to Kauai, and it seems the OP has been before so I am sort of hijacking a thread, you will find that Lihuie and Kapaa both have their own tropical version of rush hour congestion (especially Kapaa), Whatever else you plan to do, it is a good plan to see Kapaa and north from a hotel in Kapaa or north, and Lihuie and west from a hotel in Lihuie or south/west of there.