Ko'Olina was what made us fall in love with timeshares. My family also prefers Oahu as an island because of the variety, but the lushness of Kaui, the beauty of Maui. etc., are all outstanding and really a matter of personal preference.
That said, it is a long trip from the East coast. If I lived in California I would have bought there in a heartbeat. But those 12 hour trips are not something I want to do every year, and it doesn't sound like you do either. Given the high MF's I would think twice before buying a Hawaii week to trade or rent 80% of the time.
In fact, although the economy has depressed rental rates, until the past two years there were other locations that commanded higher rental rates. Between 2006 and 2009, when I followed them closely, Aruba rental rates were significantly higher, and while I haven't checked them out closely, I'm guessing that you might find comparable rental rates for other Plat. Caribbean weeks (although Aruba rental rates at least cursorily appeared to be a bit more). You might find that you would enjoy going to the Caribbean almost as much but due to the proximity might use it more often, pay lower MF's, and still have a good rental property when desired.
We decided to purchase in Aruba as an alternative to Ko'Olina, since it was a top trader in II, commanded premium rental rates, was a four and a half hour flight, and it was an island we loved. Well, fast forward a few years- we found we love to return there (even though heretofore I was a very active vacationer, with my family quipping that they always needed a vacation from one of my vacations), I actually discovered the joys of vacationing and just relaxing and reading a book or taking a walk on the beach, and we find ourselves not anxiously trading to go elsewhere, nor do we give up our usage to rent. It is also a great property for direct trading, as we are doing this summer, so that's another option.
Anyway, just food for thought.