The Egyptian Book of the Dead — the most important religious text of ancient Egypt, passages from which cover the walls of most of the tombs you will visit. Any modern translation (E.A. Wallis Budge's is old but freely available; the recent Penguin edition translated by Faulkner is better) will make the tomb paintings comprehensible rather than decorative.
The Murder of Tutankhamen by Bob Brier — a forensic examination of evidence suggesting Tutankhamun was murdered by his vizier Ay. More serious than the title suggests, and a good introduction to the politics of the late 18th dynasty. Read it before visiting the tomb.
Egypt Uncovered by Vivian Davies and Renée Friedman — a broad overview of Egyptian archaeology that covers Luxor well, with good photographs and accessible writing. Useful background before a visit.
Death on the Nile by Agatha Christie — set partly on a Nile cruise and partly at the Cataract Hotel in Aswan. Not great literature but an authentic period piece of 1930s Upper Egypt travel, and Christie understood the landscape. Agatha Christie wrote part of it at the Winter Palace Hotel in Luxor.
The Rise and Fall of Ancient Egypt by Toby Wilkinson — a chronological history of pharaonic Egypt from Narmer to Cleopatra. Dense but readable, it gives the context that makes the temples and tombs coherent rather than merely spectacular.