CaribbeanBound

cr8tiv1's advice is very good. Also agree with scottca075 Traffic is very heavy. Allow lots of extra time to get anywhere.

We're going to be in Boston in late August and the hotel prices are even higher than you are quoting here (and the points costs are also ridiculously high). I worked on this question predicament for several days before an inspiration hit me. I ended up booking at the Quincy Marriott which is 30 minutes or so from downtown Boston on the Red T line. Not ideal of course but 1/3 the cost in money or points. The station is a few blocks from the hotel and Marriott provides a free shuttle.

You can also whale watch from the beach in Kauai when in-season.

Agree the beach near Kauai pier is AWESOME and isn't likely to be real busy. In Honolulu there is NOT a close beach to walk to. You can however take The Bus from the pier to Ala Moana Beach Park (about 10-15 minutes) which is a lot closer to the pier than Waikiki Beach. When pau (done) with your beach time, the Ala Moana Shopping Center (largest open air shopping mall in the USA with more than 350 shops and restaurants and over 160 dining options) is just across the street, which is where you would pick up the bus anyway to return to the pier.