The Viking Age: A Reader edited by Angus A. Somerville and R. Andrew McDonald — A well-chosen anthology of primary sources covering the Varangian world, including the Norse settlements and trade routes that ran through Ladoga. Good background reading on the Rus and their origins before visiting.
Natasha's Dance: A Cultural History of Russia by Orlando Figes — A wide-ranging history of Russian culture from the medieval period to the 20th century. The chapters on the deep roots of Russian identity and the relationship between landscape and national feeling are particularly relevant to a visit to a place like Staraya Ladoga.
The Architecture of the Russian North — Various academic editions exist covering the wooden churches and stone monasteries of northern Russia, including the Novgorod and Ladoga region. Worth seeking out for anyone with a particular interest in medieval Russian architecture.
Medieval Russia, 980–1584 by Janet Martin — A scholarly but readable account of the Kievan Rus and the principalities that followed, with good coverage of the Novgorod lands and the role of the northern trade routes through which Ladoga was a key node.