If you study African Diaspora, Cornell is the bomb. Salah Hassan and Cheryl Finley are amazing. Very nurturing faculty. But Ithaca is not my cup of tea, being a city girl myself. Not sure about Santa Cruz's program, but if it too has awesome Diaspora people, I'd go there. Prestige only goes so far. The main things you should be worrying about is $ (which doesn't seem to be an issue for you), faculty, and resources available (resources meaning networking, neighboring institutions, archives, etc).