There are many a GI in the NY City! My IBD Daughter moved from Michigan to NYC/Lower Manhattan almost 2 years ago and hooked up with GI/Immunologist Dr. Lloyd Mayer out of Mt. Sinai (212-659-9266). She loves him, but downside is he is only in office a couple days a week and he doesn't take her insurance but her Remicade has been covered. I think she said his Office is somewhere in Harlem area(?)
I have a pretty extensive list of 120 NY GIs that I printed out from www.castleconnolly.com It tells what each GI's specialty is, if they accept PPO/HMOs and their credentials.