Moving away from fiction, literary or otherwise, I'd like to share a couple quotes from history makers. These are long sentences, well-written and easily understood.
1. Macbeth's self-justifications were feeble – and his conscience devoured him. Yes, even Iago was a little lamb, too. The imagination and spiritual strength of Shakespeare's evildoers stopped short at a dozen corpses. Because they had no ideology. Ideology – that is what gives evildoing its long-sought justification and gives the evildoer the necessary steadfastness and determination. That is the social theory which helps to make his acts seem good instead of bad in his own and others' eyes.... That was how the agents of the Inquisition fortified their wills: by invoking Christianity; the conquerors of foreign lands, by extolling the grandeur of their Motherland; the colonizers, by civilization; the Nazis, by race; and the Jacobins (early and late), by equality, brotherhood, and the happiness of future generations.... Without evildoers there would have been no Archipelago."
—Aleksandr Solzhenitsyn, Chapter 4, p. 173, The Gulag Archipelago
2. “Temperance is love surrendering itself wholly to Him who is its object; courage is love bearing all things gladly for the sake of Him who is its object; justice is love serving only Him who is its object, and therefore rightly ruling; prudence is love making wise distinction between what hinders and what helps itself.”
--St. Augustine
In his Confessions, his entire first chapter is almost a single sentence.
I am by no means comparing myself to these men, but just pointing out that correctly constructed and properly punctuated, long sentences can be captivating.