Not sure about the HGI as it is not open yet. It will be new in Aug. So nothing to say about it.

I like both the Doubletree and Hilton on KUHIO.

The lounge at the Hilton is very very basic in the basement. Soft drinks all day and cookies. At night 2 hot items but the lounge could be full of people sucking down the food. Breakfast is also just ok, few hot items. Also can be very packed. Upgrade have been nice for me as a Diamond. Always get ocean view on upper floor and a corner room with wrap around balcony. The 24/7 restaurant is more like a diner. Good but not a typical full service hotel restaurant.

Doubletree is also good. Breakfast is limited for gold/diamonds just cold items with up-charge to full. I have gotten suite upgrades a good bit they have a good number of them. I think the Hilton on Kuhio has bigger standard rooms and if you get a view it is better on the upper floors at the Hilton. The Doubletree you need to look around to see the ocean. Bar and Restaurant is small and only open for dinner. (and breakfast)

If you can get the Village on points and they will NOT hit you with the resort fee. They give 10$ per person food/drink credit for Gold/Diamond. (i always book a room for 2 even if 1 staying.. ) You can add up the certs and use them all at once. It is a zoo at that place in the summer. Upgrades are hit and miss. I have been luck with ocean fronts and Ali' tower suites mostly off season.

PM me if you have more questions. I live on Oahu and have been to all the Hiltons in town many times and have some contacts.