I have stayed at the JW numerous times on family vacations and we absolutely love it! It is a true resort - wonderful spa and fantastic pool. The pool does close for the winter (as of Dec. 1), so keep that in mind if taking the family. We will be there over Thanksgiving and can't wait!
I have never received an upgrade at the JW, but you don't really need one. Their standard rooms are quite large and have elegant bathrooms with whirlpool tubs and rainforest showers. (I've always stayed on a "Friends & Family" rate which is not eligible for upgrades...
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The casino is attached, but not owned by JW - it is the Rampart Casino. It has mostly locals there, and usually has better odds than strip casinos. It is about a 20 minute drive to the strip and rental cars are cheap in Vegas. Most hotels do not charge for parking - just a tip for the valet.