My experience when trying to book SLH hotels through Hyatt.com is that there is often limited to no availability whereas if you go to the SLH website there is lots of availability. For example we spent a month in France in August and tried many times to book SLH hotels through Hyatt - no availability and yet those same hotels we booked through SLH. For example we spent 14 nights at the Tiara Miramar Beach Hotel on the French Riviera - no availability on Hyatt.com both then and none as far as I can see in the future. We booked direct with SLH and there was and is lots of availability.