If you have any interest whatsoever in Westerns as a genre you should read Lonesome Dove. It's about 850 pages but I'd be surprised if it took you more than a week to read. For the longest time I had no interest in reading it because, of all the things, the title put me off (I thought it would be a romance of some sort).
His uncles were cowboys toward the end of the cowboy days, and when they were young, they'd heard stories from the old-timers about how things used to be. Those uncles told Larry those stories and he eventually incorporated that knowledge into his westerns, and it really shows. One thing I find fascinating about Lonesome Dove is that, as the article says, he intended it to deconstruct some of the myths of the West and show what a hard life it was, but everyone who reads it falls in love with the world and the characters.