The Ace Hotel has a great lobby to work in. I work there for a couple hours almost every trip I make to NY.
Convenient outlets at most seats, free wifi, and a Stumptown adjoined!
Lot's of creative types working there, illustrators, writers and such. Can get pretty busy after 5pm.
http://www.fastcompany.com/1768472/ace-hotels-communal-works...
20 West 29th Street New York, NY 10001