I currently use a 24" monitor on my home setup and a 24" + laptop screen at work. Usually placing the 24" screen above the laptop. The main screen changes throughout the day, but the larger screen is always preferred.
HN Thread with a lot of reference for other people's setups, including multi-portrait displays, using TVs and such. I'm interested to trying out a 4k TV for my main setup at home, but alas, no money for it now.