Seems like the sign-up bonus will get you only one free night, in most cases.
A property in Scottsdale, AZ is close to 18,000 a night; one in San Jose, Costa Rica
is close to 16,000; and one outside London is a little over 18,000.
With a higher sign-up bonus they would likely get a greater number of applicants.
And much more exposure to their hotel brands.