New York and San Francisco are the most expensive flexible office markets globally, according to Workthere, Savills' flexible office brokerage.

Private office desk spaces in New York cost an average of $961 per month, followed by San Francisco with a monthly price of $950. And office occupiers appear to be seeking quality assets above all else, according to Griffin Foley, Northeast Lead, Workthere Americas at Savills.  

"The flexible market is now dominated by high quality spaces because occupiers are focused on cultivating an updated office strategy around a space employees want to be in, and in an environment that enhances their desired culture," he said.  "Similar to the Manhattan office market as a whole, there has been an undeniable flight to quality which has resulted in a shrunken set of options to choose from and ultimately higher asking rents."