I haven't stayed at the JW (I usually stay at the Ritz). Stayed at Casa Magna years ago, and liked it. I note that if you use points at the JW you can upgrade to one of their club room floors for $100/nt. From the description in the rate rules, it seems to be a copy of a Ritz-Carlton Club floor, and can save you a decent amount of money you would otherwise spend on breakfast, airport transportation, drinks, other meals, internet access, etc. (it doesn't say it here, but I think it also includes free access to the second floor spa facilities, they otherwise have a $10 per person per day charge):

CLUB 91 AND CLUB 91 LOUNGE INFORMATION
*** IMPORTANT NOTE CLUB 91 LOUNGE ACCESS IS FOR MAXIMUM OF 2
ADULTS (16 YEARS OR OLDER). ADDITIONAL GUESTS BROUGHT TO THE
LOUNGE WILL INCUR A 50 USD DAILY MEMBERSHIP FEE. ANYONE UNDER
16 MUST BE ACCOMPANIED BY AN ADULT ****
************************ IMPORTANT ****************************
CLUB 91 IS NOT A CONCIERGE LEVEL OR EXECUTIVE LOUNGE AND IS
AVAILABLE ONLY THROUGH CLUB RATES*****
************************************************** *************
* UPGRADED SERVICES AND AMENITIES ON PRIVATE FLOOR
* COMPLIMENTARY AIRPORT TRANSPORTATION (FOR 2 ADULTS ONLY)
HOTEL WILL CONTACT GUEST VIA E-MAIL FOR FLIGHT INFORMATION
ADDITIONAL PASSANGERS WILL BE CHARGED 18 USD ROUND TRIP.
UP TO TWO KIDS UNDER 12 ARE FREE.
* CLUB 91 LOUNGE - EXCLUSIVE KEY ACCESS, SELECTION OF CD'S
BOOKS, GAMES, PERIODICALS AND NEWSPAPERS
* CLUB 91 LOUNGE HAS FIVE DAILY FOOD PRESENTATIONS
* GUARDIAN ANGEL SERVICES - UNPACKING/PACKING, PRESSING,
SHOESHINE, PERSONAL SHOPPER, SERVICES UPON REQUEST
* SLEEP IN COMFORT - A VARIETY OF PILLOWS, MASKS TO CHOOSE FROM
* BATH AND BODY - VARIETY OF SOAPS, BATH SALTS AND SHOWER GELS
* PREMIUM OPEN BAR FROM 6PM TO 8PM