Wynn and Encore in Las Vegas are offering first night free on a minimum two night stay through the American Express Fine Hotels and Resorts program (for Platinum and Centurion cardmembers).
You can only use the offer once, for a booking made by April 15 and stay through June 30. Standard American Express Fine Hotels and Resorts benefits apply.
Promotion code is E1320542 and the offer can be booked at the American Express Fine Hotels and Resorts online booking site. Flyertalk discussion of the deal is here.
