I've been to Hawaii several times. I strongly suggest splitting your time between two islands, especially if you don't think you will be heading back any time soon. Island hop flights are cheap, quick, and always on time.
On Oahu I've stayed at:
Hilton Hawaiian Village - Loved it. The beach is great, so much bigger and nicer than the "busier" part of Waikiki. You are still within walking distance of everything, but less busy.
Outrigger - Middle of the road, but not bad. Great location. Noisy. The bar facing the ocean is amazing.
Sheraton - They have a super cheap annex room, as opposed to the main building. No ocean view so you save a lot, but it is like a college dorm room. Pay a bit more and avoid this room.
Turtle Bay Resort - North Shore. Very nice. Watching Forgetting Sarah Marshall to see the resort as it was filmed there. Not much to do outside the resort though. If just staying on Oahu, it is a good 2 day destination and the Dole plantation is halfway from Honolulu on the way to Turtle Bay.
Big Island:
Hapuna Beach Prince - Amazing beach. Amazing pool, although bath water temperature which annoys some. A great hotel, a great view, and the beach is perfect with snorkel and body surfing opportunities right there. But the island is boring, Volcano NP is far away from this hotel.
Hilton Waikoloa - Huge. Disney like. Have monorail and boats to get around the resort. The pools are very nice, but super cold. Crazy cold. No real beach to speak of.
Maui:
Best overall island in my opinion. Stayed at Hyatt and thought it was pretty good. The pool is nice, but no real beach. A short 5 minute walk gets you a good beach. Very active and busy.
Four Seasons - Great hotel. Great pool. Great food, and next to great hotels and food options too. Beach is nice, only shared with 1 other hotel. Service is amazing. Deals can be found, not as expensive as you would think.
Kauai:
Hyatt - loved the beach. In winter it gets serious 10' waves, and is actually slightly dangerous. Made body boarding tough but awesome. In winter time the waves will knock people over, not North Shore big, but the rocky coast makes it dangerous. Hotel was great and the pool was awesome. Lazy river was nice too.