Have stayed at and liked them very much. Though the two proterties meet different needs and both are very different than The Strip's hotels. But that is a good thing for me as my tolerance for the Vegas 'scene' is pretty low as a few hours is all I can take of Casino fare.
The Suites is a business Oasis just across from the convention center. If work is why you are in Vegas stay here, and you want insulation (not everyone does
) from the Casinos, tourists, etc. there is no better place to stay. But the strip is still just a couple of blocks away an easy walk or there is also close access to the people mover.
The JW is a true resort and removed from the city entirely. I would only stay here on a personal vacation that did not include plans for alot of time on The Strip. Other than that I can't add much to the previous posts, other than to echo it is one of the best Marriott propteries I have visited.