When in Egypt, I found some relevant books on Alexandria. The American University Press in Cairo has an excellent bookstore in Cairo, and publishes regularly a lot of books relevant both for present days and ancient Egypt.
Concerning Alexandria, there is a couple of tourist guides you might want to consult if travelling: first and foremost, there is the Lonely Planet volume on Egypt in general:
A Travellers Guide.
Then there is another focusing more on Alexandria:
Jenny Jobbins & Mary Megalli,
Alexandria and the Egyptian Mediterranean.
The American University in Cairo Press, Cairo 1993/2006.
More, relevant perhaps, are these volumes focusing ecplicitly on Alexandria:
Alexandria. City of Memory
The American University in Cairo Press, Cairo 2004
Anthony Hirst & Michael Silk,
Alexandria. Real and Imagined.
The American University in Cairo Press, Cairo 2006.
This latter volume contains several articles that are very relevant for those interested in Alexandria in Graeco-Roman times.