Middlemarch

It has a multiple plot with a large cast of characters, and in addition to its distinct though interlocking narratives it pursues a number of underlying themes, including the status of women, the nature of marriage, idealism and self-interest, religion and hypocrisy, political reform, and education. The pace is leisurely, the tone is mildly didactic (with an authorial voice that occasionally bursts through the narrative), and the canvas is very broad.