Understand that there are two Westins: A timeshare condo complex north of Black Rock (the Ocean Resort Villas) and a (rather crummy) resort hotel (Maui Resort and Spa) next door to Whaler's Village.

kaanapaliresort.com/About/resortMap.aspx

Here's a map. The Westin is letter A and MOC is letter K.

We have stayed at the Westin Resort and Spa 6 or 7 times and love it. The location is phenomenal, the beds rock, the rooms are nice, and we love the pool. We haven't stayed at the Marriott, but have eaten at their restaurant and it is a lovely property as well. I don't know about the Marriott, but the Westin has an 'adults only' pool, which I really appreciate when we are there without the kids.

BLBL, I am curious why you refer to it as 'crummy'? In what ways do you feel it is inferior to other properties in the area? Do you like the Sheraton BlackRock better?

Sheraton Maui on Black Rock is much better.

Westin Resort and Spa - noisy; oddly-designed rooms that make them seem small; no "grounds" - only stacked pools; people traipsing by constantly (Whaler's Village draws them); non Hawaiian or mixed decor; kid-magnet.

BLBL thanks for your input. While we have never found it to be noisy, nor do we find the rooms to be small, we will definitely wander down to the Sheraton to check out their rooms on this trip, for future reference. We are also not bothered by the people traipsing by, although I can see how the Sheraton would be much less trafficked in that respect given its location. Good stuff for people to know, though, in case they would be bothered by those issues.

Yep, BLBL, we'll just have to agree to disagree about the Westin. Our experiences were very different from yours. Our room, fairly small but clean and updated. Wasn't over the top luxury by any means and a bit average but worked out fine for us. Found the marble common areas luxurious. Surprisingly few kids there but of course schools were in session. Our room was, well, square or rectangle and certainly wasn't oddly shaped. Some may find the sound of the waterfall "noisy" but we found it soothing and enjoyed having coffee at a table close-by, while enjoying the exotic birds. Yes, the whole area is more "closed in" than the Sheraton which does add a bit more noise but we didn't find it annoying so. We adored the pools and even though we had great fun in the Sheraton's "lazy river," the Westin's very extensive pool area gave us many more pool options. It was fun to be so close to Whaler's Village and its restaurants. We also loved the Sheraton (particulary when staying on Black Rock) and give it a bit of an edge since we loved to be so close to snorkeling, but would stay at the Westin again in a heartbeat.

Addition: I timed out on my edit. I would add though that due to extra space/sitting area/cooking facilities I would choose the MOC. Just more bang for the buck than a plain hotel room and would have at least some of the other hotel-type amenities including great pool area. Beach isn't quite as good there but improves with a fairly short walk.

Are you talking about the Westin villas? Well, then I'd choose....either. MOC more in the thick of things but Westin Villas also in a great area. Actually, since the snorkeling area directly in front of the Westin Villas is one of our favorites, that would probably be my choice. Really can't go wrong either way.

Yes, Greenvalley, you caught it, as stated in the OP's title, they are talking about the two time-shares.

We have stayed at the Ocean Club. Will be there again July. We enjoy our time there. Great location. units and the grounds are great. pool gets crowded early. Seems repeat visitors want to sit at the pool. It's Maui! We like to go out and about the island, Great place to sit in late afternoon.

Have fun

Safe travels