Hawaii is one of the concierge buildings--Tonga the other. The latter consists primarily of suites and is located adjacent to the GCH. Hawaii is beachfront facing the castle and between the volcano and quiet pool. You will not be able to use Hawaii as a food service source unless you are staying concierge.
Captain Cook's will be relocating to a building which houses The Neverland Club, laundry, and arcade. There is a separate side to this building that is used primarily for accommodating large private functions, i.e., weddings, receptions, etc. It is equipped and was, in fact, previously used as a restaurant facility at the resort. Steve's site will give you the proposed dates for the relocation--I'm thinking he said it was June-August????, but don't quote me on that because I can't recall the exact time frame. In any event, there will be a "fast food" type location for refillable mugs, quick service, etc. I am not sure--and I'm not sure if Steve knows for certain--what the food offerings will be during the relocation. I would imagine the offerings would be similar to what is currently available. The space in Tangaroa Terrace is fairly large.
Steve's site will also give you up to date information about building rehabs. If I recall correctly, Tahiti and Rarotonga are scheduled to be remodeled during the summer months, e.g., July and August (perhaps late June)--again, don't quote me, I'm going from my memory of events.
As to your "perfect" room location, I have two in mind--Samoa would be close to both pools and the GCH, but no monorail view. Nuie would also be close to both pools--again no monorail view. Tokelau would also be a great option, close to the quiet pool, not too far from the volcano, and very near the relocated Captain Cook's, arcade, The Neverland Club, laundry, and bus stop. If you want a monorail view, you will be on the exterior facing side of any of the longhouses adjacent to the monorail line. Hence, you would be away from the pools, but still not far from anything.
Samoa, Nuie, and Tokelau offer great pool/garden views and are centrally located within the resort. For me, anywhere you stay at Polynesian will have benefits and it's very hard to say one is more perfect than the next. I hope this narrows down your choices. That said, if you look at a map of the property (check out Steve's website) you will have a really good idea of what appeals to your heart's desire.
Good luck making your decision! Polynesian is certainly our favorite resort at WDW.
Well so much for my theory 
