Well, as someone who bought one of each this month, here's my opinion....Ko Olina is all new, "purpose built" Marriott-style T/S units. They are very nice. We own Grande Vista, too, and those new units are nicer in my opinion (also considerably bigger). I was very impressed with the richer, darker new Marriott decorating in Ko Olina as well as the newer-style hardwood floors in entry areas (this seems to be the new trend like at Surfwatch). The pools at Ko Olina are great. Instead of one gigantic pool you get a couple with the typical hot tubs scattered around. The beach at Ko Olina is kind of off to the side, and is man-made but very nice. It is a crescent shaped lagoon which is great for swimming and snorkelling. There is a big Marketplace at Ko Olina and a nice pool bar/restaurant right on the ocean. You can walk to the JW Marriott (at the other end of this Marriott area) and eat at their restaurants or use their spa (all pretty pricey). There is Roy's on the golf course (which is right there at the resort) and is another expensive but very good resaurant. Other than that, you face a 5 minute car trip to Outback, etc. for restaurants or food shopping. One thing that concerned me at Ko Olina was that the resort is still in construction (with, I think, 2 or 3 more buildings to go in) but even more than that is the nearby construction. If you are buying an "ocean view", who knows what you will eventually see. Trump just bought a few acres next door and right on the ocean (near the man made beaches). Sales at Ko Olina ignored my observation that Trump does not build 2 story buildings, and this one would block most of the ocean view for many of the units sold with that designation. There is expensive private housing going in next door now, but that won't have any detrimental effect on Ko Olina B.C.. I think this resort is great overall, and down the road it looks pretty good that this area, although still nearby a refinery and power plant, will become more and more an upscale resort area.
Regarding the Maui Ocean Club--we toured there with no buying intentions just to see it. I was not really interested in hotel conversion at all. However, we were so impressed with the resort location and especially that pool that we bought the cheapest view they had there. We bought in the old hotel part, and did not see (none are done yet) any of the new units in the one new "purpose built" t/s building going up next door. I think these will be comparable to Ko Olina and the other new Marriotts, although it seems the Hawaii units have somewhat smaller square footage. The hotel part was actually very nice. I had expected something like the "deluxe hotel room" part of a lockoff, but there is a dishwasher, full sink, half-sized refrigerator (all we ever used anyway) and some facility for limited cooking plus outdoor grills in the pool area. The fitness center is new and very good (they apparently converted some old stores over to it--a large and complete center with a massage area and steam room). The public areas of this resort are just beautiful. So nice, in fact, that there is apparently some concern that the general public tries to sneak in and use them, making it more crowded than it should be. I did not see a marketplace here, but there are several regular retail stores which appear to be holdovers from when this was a regular hotel. There is other shopping and several nice restaurants a short walk away, plus a whole bunch of other resorts in this immediate area. The beach here is one of the best I've ever seen. You cannot understate the sunsets here (we took one from Lahaina-5 min away- and blew it up to a Kodak 20x30 print--prettiest picture I ever took). Anyhow, the newer units are VERY expensive, do not have an EOY option, but should be the cream of the crop when done on, basically, the best location Marriott has (or at least the most requested). We bought a view of the next-door golf course (cheapest but still pretty nice) for a price much lower than I expected. We totally changed our mind on this resort when we saw what we could get a unit for EOY in the older hotel part. The rest of the resort and the general area it is in is fantastic. Which is better? I honestly don't know. My suspicion is Ko Olina will be quieter for awhile, with less pool crowds, etc. It is kind of off by itself, at least at the moment. M.O.C. is in the middle of a very popular resort area and maybe has the best pool are of all the hotels and resorts there. The pool area was VERY crowded (around the pool, not so bad in it).