Don't forget Kings Land which is still under construction.
The island is called "Hawai'i" aka the Big Island of Hawaii. I believe Kona is a district in the north-eastern part of the Big Island.
All three TS are co-located in the same area (Waikoloa Resorts)
The Bay Club: HGVC affiliate resort. Not all owners are part of the Club. The ones that are, paid to be part of the Club. The Resort is older, but have a larger living area than Waikoloa (no experience just read in a previous post). People staying at Bay Club must pay to use the swimming pools at the Hilton Hotels.
Waikoloa: Newer resort. All rooms are 2 bdrms and 2 baths units. Rooms are divided into 2bdrm, 2bdrm plus, 2bdrm premier. Difference is the view and furnishings. Parking lot, Garden, Golf Course view. Also have free use of the pools at Hilton Hotel; which they provide a shuttle.
King Land: Still under construction. Highly anticipated because of the mega-pool complex with slide that is suppose to be built. High point cost just to stay in a 1 bdrm (9300pts for a week in Platinum Season). There is only 10 weeks that are consider gold in which 1 bdrm cost 6300 pts. The question owners have from the other two resorts; is will they be able to use the mega-pool when it opens.
This is the webpage to the members guide
http://www.hiltongrandvacations.com/mg/ You do not need to be a member to see the guide.