This photo was for sale on eBay a while back, and was advertised as being taken in a New York City hotel.
Head premiered in New York City on November 6, 1968 and The Monkees stayed at the Hilton Hotel. I'm wondering if the photo above comes from this time period.
Andrew Sandoval writes the following in his book detailing the events of November 6, 1968:
"The Monkees travel to New York City to attend the premiere of their movie Head, which is held not in a cinema but rather at the Columbia Pictures studio on West 54th Street. A party is thrown afterwards for guests including Janis Ian, Andy Warhol, Boyce & Hart, Carole Bayer, Lester Sill, Bert Schneider, Bob Rafelson, Peter Fonda, Peter's brother Nick Thorkelson and his grandma. A discotheque is set up and a room that includes small television sets playing portions of the movie. (The group stay at the Hilton hotel.)"