Agree with others that DoubleTree is not a great location, and is not any closer (time wise) to Pearl Harbor. The HR is HUGE, but is in a great location, directly across from beach and in the center of Waikiki action.
Were I to choose between DoubleTree x Gold or HR x Diamond, I would go with the HR. Much better chance for upgrade to higher floor with spectacular ocean/beach view.
As a vet, have you considered any of the Military Lodging options?
Lots of facilities on Oahu, including Waikiki and Pearl Harbor. Hale Koa is nice, with a great beachfront location, and much more reasonable rates for rooms, parking, food and bars. Never been to Navy Lodge Pearl Harbor, but sure would be unique way to visit Pearl Harbor. Also very close to Airport.
I would take best deal in Waikiki at either Hale Koa or HR, then visit Pearl Harbor and spend last night at Navy Lodge, if available.
(Availability at Navy Lodge Pearl Harbor looks s
Hale Koa
http://www.halekoa.com/
Navy Lodge Pearl Harbor
https://www.navy-lodge.com/lodge_pag...odge_number=19
IHG Army Hotels
http://www.himwr.com/recreation-and-...hg-army-hotels