Your 1st area isn’t Midtown. Guggenheim is at 5th and 89th. AMNH is at CP West and 79th. You have to walk through Central Park to get between them. The Neue Galerie is near the Gugg at 86th and specializes in German/Austrian arts and design. Lots of Klimt and stuff like that. Lots of people just go to just to eat at the Viennese-style Cafe Sabarsky. The New York Historical Society Museum is overlooked and right across the street from AMNH.