I am a Dallas-based chowhound visiting Manhattan, who happened to have a very good (to great) bouillabaisse in -- of all places -- a hotel restaurant, and thought I would pass it along. It's at The Black Duck, the restaurant attached to the Park South Hotel, on 28th between Park and Lexington.
The dish is a huge portion of salmon, shrimp, scallops, mussels and clams (plus linguiça) in a very well seasoned, garlicky saffron broth. It comes topped with a hunk (no other way to describe it) of grilled bread spread with a very nice rouille. Price is $23; it could easily serve two people.
The restaurant itself is a nice, small bistro-style place with great service and good French electro-jazz playing on the sound system.