I think the best perk is the free internet access which can save you $10-$20+ a day. Other than that, not much else except for the little benefits, such as "best available room within the booked category" which doesn't mean much, maybe a higher floor room or with a better view, but that depends on your luck at the hotel. Bonus points, priority check in (which I've yet to make use of as every single Hyatt I've stayed yet either had no one at this desk or everyone else was using it so I believe it's not at all reinforced).