Ric Garrido of Loyalty Traveler has a thorough update and analysis of this promo:

Some details of interest that are new to me include:
Radisson promo open to first 100,000 registrants for 50,000 points. After 100,000, registrants will earn 15,000 points.
Country Inn promo open to first 35,000 registrants for 44,000 points. After 35,000, registrants will earn 15,000 points
Park Inn promo open to first 20,000 registrants and begins on May 22. After 20,000, registrants will earn 15,000 points

Also, please note that Ric says:
"Here are terms I have confirmed with Club Carlson.

Club Carlson members can register for each brand promotion and earn all three bonuses.
Reservations made prior to the promotion launch for stays during the May-July promotion period are eligible for the bonus points.
Points + Cash stays are eligible for promotion bonuses."

Full write-up is here:
http://boardingarea.com/blogs/loyal...aign=Feed: LoyaltyTraveler (Loyalty Traveler)