(updated September 12, 2018)
NOTE: As of September 12, 2018, seasonal Rewards for Fall 2018 have not been released.

myVEGAS’s 2 Night Comp Room Rewards come in two different flavors. Everyone who plays should be able to see the seasonal 2 Comp Nights Rewards (like the   2 Comp Nights: Spring 2018).
If you purchase chips, though, you may be able to get non-seasonal Two Comp Room Nights Rewards (the different spelling is intentional – myVEGAS uses the number 2 for the seasonal Rewards and spells out two for the regular Rewards).

Two Comp Nights  Rewards are available for all MGM Las Vegas hotels except Circus Circus.

With the exception of the Luxor, the regular Two Comp Room Nights  Rewards are cheaper than the seasonal Rewards. The Two Comp Room Nights Rewards have their own availability calendars which you can see in my Comp Room Rewards calendars post.