Travel Guides
Rick Steves Germany — Updated annually, practical and opinionated, excellent for first-time visitors. Strong on the Bavaria-Rhineland circuit and Berlin.
Lonely Planet Germany — Good all-round coverage, better than most for eastern Germany and off-the-beaten-path destinations.
History
Germania by Simon Winder — A genial, oddly personal journey through German history, focussing on the small states and princely eccentricities rather than the big dark episodes. Surprisingly good company.
The Anatomy of Fascism by Robert O. Paxton — Not Germany-specific, but essential for understanding how it happened. Better than most books focused only on Hitler.
Stalingrad by Antony Beevor — The definitive account of the battle that broke the Eastern Front. Harrowing and authoritative.
Berlin: The Downfall 1945 by Antony Beevor — A companion volume covering the last months of the war in Germany.
Fiction and Literature
All Quiet on the Western Front by Erich Maria Remarque — The definitive anti-war novel, written by a German about German soldiers in World War One. Still devastating.
Faust by Johann Wolfgang von Goethe — The defining work of German literature. Faust Part One at least is accessible; Part Two is a slog even in German.
Buddenbrooks by Thomas Mann — A portrait of a Lübeck merchant family's decline over generations. Mann's most readable novel.
Berlin Alexanderplatz by Alfred Döblin — The great Weimar Republic Berlin novel, raw and modernist, set in the working-class streets of 1920s Berlin.
The Reader by Bernhard Schlink — A short, morally uncomfortable novel about guilt, complicity, and the postwar generation. Widely read in Germany.