I've been to both hotels in Rio & SP and I agree the charges are beyond excessive.

At The JW Marriott in Rio having lounge access saved me BIG $ on breakfast and the internet was free on the computer located in the lounge.

BTW, you are very correct in using points at JW Marriott RIO... I booked 7 nights over New Years with my travel package. ^

I'm sure you are aware, The JW Marriott RIO only sells packages with a 5 night minimum over New Years starting at $2500USD