One of the best books of medieval history I've ever seen is C. Warren Hollister's Medieval Europe: A Short History He strikes a healthy balance between political, cultural, and religious history. He is very fair in his treatment of the Church. He neither glorifies her or vilifies her.
He is clearly sympathetic with the pious aspirations of the people, and is critical of the hierarchy when they let their political ambitions get in the way of their real duty as spiritual fathers and ministers of the Gospel of Jesus Christ. For instance, he praises the genuine religious fervor of the first few of 11th and 12th century reform popes, but is critical of the later ones, especially Innocent III, for putting too much emphasis on temporal, political goals, thereby alienating the people, who hunger for spiritual food, from the clergy.
He does not see piety as a negative trait, although he clearly distinguishes it from holiness. He is especially glowing in his treatment of St. Louis, and his pious mother, Blanche of Castile, emphasizing their earnestness and success at establishing a just, Christian realm.
It is very interesting to compare the Hollister's treatment of medieval saints to that of Hugh Ross Williamson in the wonderful book, The Young People's Book of Saints. There are no real contradictions, but the emphasis is different. Hildebrand, for instance, is never called a saint by Hollister, although his zeal and high purpose is acknowledged. Williamson, on the other hand, clearly sees St. Gregory VII as the tragic hero-saint in the conflict with Henry.
I highly recommend both books.