I've had the same experience at the Willard twice combining paid and points stays within the past year (after they tightened up their award night benefits).
Also had good luck at De La Ville Roma where I booked one night in their Junior Suite w/ Terrace followed by six award nights. I was given the option at the front desk of upgrading to the Penthouse for one night and then their Classic room for the rest of the stay or remain in the junior suite for the entire stay. I took the latter and couldn't have been happier with full benefits throughout.