My hsband and I recently stayed at the very nice Sawgrass resort in Ponte Vedra, FL, using some of our Marriott Reward points. We were dismayed to find that internet access was charged (and at 12.95/day). It was also rather cumbersome to access. This makes no sense to us since virtually all of the other Marriott properties provide it free and easy. We believe it should be free throughout the system, at least for Elite members.
It appears that each hotel and each brand has its own policy. Some Marriott hotels provie complimentary internet, but most I have stayed at do not, even for gold/platinum. Some have complimentary internet in the business center, while others charge for use. It is best to check ahead of time. Springhill, Courtyard, and Residence seem more likely to provide complimentary access.