Hi Greg,
In addition to the classics already mentioned, Anway Mukhopadhyay's "Devī As Corpse" has some interesting work and interpretations of the Śaktipīṭhas.
For some useful maps of various Śākta pīṭhas, Mark Dyczkowski's chapter "The Inner Pilgrimage of the Tantras" in his "A Journey in the World of Tantras" book, has a number of maps outlining sacred sites from the Kubjikāmatatantra, JRY, Manthānabhairavatantra, etc., plus many charts and info on their inner equivalence within/on the body.
Best wishes,
Brian Campbell