Marriott is all time share. I have owned there for years, and been many times.
We were stationed at KBay for 3 years as well, and I had our son at Tripler.
I would recommend looking into the Marriott if you want to get away from Waikiki! It's relaxing and much much more spread out than Aulani is. You can book nightly rates through Marriott, as you can at any Marriott timeshare. I'd check and see if they have any government rates for your dates. I'd definitely choose it over the Marriott in Waikiki. We rarely find any issue with getting a chair by the pool at Ko Olina, and there is a nice quiet pool as well. I don't care for Longboard's though - we mostly cook in our eat out for a big lunch (if you like sushi, don't miss Sushi Bay in Kapolei by Safeway! It's so GOOD, and yes you will wait but it's worth it).
If you want to do Waikiki, be aware that the beach near the Royal Hawaiian has diminished over the past 15 years, and it's a bit narrow now. The widest stretch of beach is actually near the Hale Koa (or the Hilton). Personally, now I find Waikiki too busy and noisy for me (sad but true). But, there is a new Embassy Suites that looks nice there now.