Robert A. Caro has written several massive volumes on Lyndon Johnson, and I suspect that his books will be considered the pinnacle of Johnson biographies for the next few centuries. Not only are they thoroughly researched (he spends about a decade writing each volume), but because he's a journalist and not a historian, his prose is gripping and interesting for the masses. That being said, what I've learned about Johnson is he was a massive asshole. I would never, ever want to work for him because he's so terrible to the people around him.

However his dickishness is sometimes hilarious:

When, during his presidency, a woman reporter wrote critical articles about him, he would tell White House counsel Harry McPherson, "What that woman needs is you. Take her out. Give her a good dinner and a good fuck." And, McPherson would learn, the President wasn't kidding. Joseph A Califano Jr., to whom McPherson related about the incident, writes that "Periodically the President would ask McPherson if he'd taken care of the reporter. Every time she took even the slightest shot at the President, he'd call Harry and tell him to go work on her." .... Califano writes that, "LBJ made a similar suggestion when I advised him of the problems James Gaither, an aide on my staff, was having on Edith Green, the irascible Democratic congresswoman from Oregon.... Johnson became irritated with our inability to deal with her. In exasperation one evening he said to me, 'Goddamn it! You've been trying to drag me into this thing when I've got a hundred other problems. Well, I'm going to tell you how to get our bill. There's no point in my calling that woman. Gaither is a good-looking boy. You tell him to call up Edith and ask her to brunch this Sunday. Then he can take her out, give her a couple of Bloody Marys, and go back to her apartment with her. Then you know what he does? Tell him to spend the afternoon in bed with her and she'll support any Goddamn bill he wants."^*

^* Robert A. Caro, The Years of Lyndon Johnson: Master of the Senate (New York: Vintage Books, 2002), 147.