Stayed here around February 2008 (two times in a couple of weeks, for 2 nights each) and had a great time - we got a room near the top on the concerige floor and had a great view of the beach/pacific, very nice rooms as well (standard Marriott executive types). Concierge lounge was, at least at the time, very generous and provided enough food to eat as a full meal if you wished several times a day (and Peruvian type food too). The other nice thing was little gifts (sweets and dolls) that they brought around each night to give to guests.
The rest of the hotel was lovely, with a very spacy enterance lobby. The location is excellent, being right across the road from a huge mall, with American food / fast-food (including all the big chains) if you'd like that kind of thing, or otherwise some very nice looking fish based restaurants with a great view of the ocean.
I was using points, but, I'm Marriott Plat (hence the upgrade), can't comment on the non-exec floors but I suspect you wouldn't get the dolls!
As another sign of how good the hotel is, its 4th best in Limaon tripadvisor, most of the reviews are very positive. Here is my review (& pictures)
here... the fact that management responds on the thread shows they care too... However, I'm sure when I booked it was the best...
I couldn't but recommend it really - I did see they were doing an elite only offer very recently (might have been plat only) in the last email I saw where you could stay 2 nights and get 1 free or similar - might not have been your original plan, but, might work out better value than points. I think that overall its a 'special' hotel so worth spending points on and staying at, but, haven't stayed at the doubletree to comment on that.