Depends on occupancy. Duration of stay. Demonstrated friendliness to registration. And, many insist, a $20. Ive been to MGM properties 7 times in past two years. Asked politely every time Upgraded twice at check in , once Bellagio to suite Reassigned to slightly nicer room within my category twice - that might have been a bit of bs Relocated to slight upgrade after check in based on unsatisfactory room. Also Bellagio... Mountain view room that stunk like an ashtray to a pool view room that was also slightly larger. Nada twice, unless I wanted to pay more.