If the president gets married in the first 50 pages, you're reading a What Kind of President Was He? biography. These get the formative years out of the way as quickly as possible, and generally eschew the personal details throughout. The Madison biography, I think it was, mentioned Dolly for the first time by saying "he was married at this point."
If the president gets married after the first 50 pages, you're reading a What Kind of Man Was He? biography. These take the time to build a character portrait. I prefer these because I am a woman and I like to empathize with people.
Margaret Leech married off McKinley with all haste so she could get right to the war stuff, which is kind of strange because her Garfield biography was the opposite.
This is just a miscellaneous McKinley fact, as are the following:
Look at how many conservatories used to take up the White House lawn. They had orange trees and all that.
In Sound Familiar? news, McKinley decided to go to war after praying about it and deciding that God wanted him to.
Ida McKinley was epileptic. Her seizures, or "fainting spells" as the McK's called them, were so frequent that she rarely left the house except at William's side. When he was governor of Ohio, they lived across the street from the state house. Every morning when he would walk across the street to work, he turn around once he got to the state house gates and wave to his wife in the parlor window. Then, at precisely 3pm every day, he would stop whatever he was doing and wave to her again from his office window with a white handkerchief. McKinley was generally a very staid man, not prone to flights of emotion, but this devotion to his wife won him many admirers.
They had no way to treat Ida's epilepsy, so their tactic was to never speak of it. Many of their friends and family had witnessed Ida's attacks, but had never heard the family explain what was going on. In fact, when an attack came on, McKinley would throw either a handkerchief or a napkin over his wife's face until it passed. Sometimes this would be in the middle of like, bridge with the Hobart's (his VP), and he would just throw the hanky, play her turn for her, remove the hanky when she stopped, and they wouldn't mention it at all. It was pretty strange, but everyone gets to experience their ailments the way they want to.
Margaret Leech is pretty good at the political biography insult. Here are my two favorites, both about McKinley's colleagues:
"Into the deep waters of the national life, the pebble of Dewey's availability [for nomination] had dropped with scarcely a trace but the widening ripples of laughter."
"After the beef inquiry, Miles rapidly declined into the political unimportance which he so richly merited."