Starwood Preferred Guest
The last Starwood Preferred Guest promotion ended July 20, 2018, and the first promotion in the new Marriott Rewards program hasn't been announced yet.
Between May 1 and August 31, 2018, earn double base Hilton Honors points on paid Hilton stays, excluding Hampton by Hilton Hotels in Mainland China. Register for the promotion here.
The last Marriott Rewards promotion ended July 20, 2018, and the first promotion in the new Marriott Rewards program hasn't been announced yet.
World of Hyatt
Between May 7 and July 31, 2018, earn 20% Bonus Points on eligible spend when you stay at Hyatt Place Las Vegas or any participating MGM Resorts destination in Las Vegas. Register for the promotion here by July 31, 2018.
Between June 1 and August 31, 2018, earn 5,000 World of Hyatt points for every 5 eligible nights you stay at a Hyatt Regency or Grand Hyatt property. Register for the promotion here by July 15, 2018.
IHG Rewards Club
Here's the list of current IHG PointsBreaks properties, for reservations made through September 30, 2018.
Between July 10 and August 31, 2018, you may be able to get a 5% or 10% discount and a $25 Amazon.com, Amazon.ca, or Starbucks gift card when you stay two or more consecutive nights, but I doubt it. Learn more about the "Treat Yourself" promotion here.