SPG (Starwood Preferred Guest) was one of three loyalty programs that were merged to create Marriott Bonvoy. Now SPG points, Marriott Rewards and Ritz-Carlton Rewards are all been converted to Marriott Bonvoy points.
At launch, many of the good features of SPG were retained. The main one lost was the breakfast benefit for SPG members who were At launch, many of the good features of SPG were retained.
The main one lost was the breakfast benefit for SPG members who were migrated to Marriott Bonvoy Gold. Since launch the value of benefits has gradually been eroded under Marriott.