I used two 24" monitors at work for years, and thought it was fantastic. But at home, I only have one 27" iMac, and it's more than enough... tried two for a while, and it just didn't help.
I think the 27" is in a sweet spot. Big enough to be able to display several things (2 editor columns + docs + console for example) but not too big so that it's not visible all at once.
Now if it would be possible to get a 27" 5k screen like the new imacs, that would be absolutely great. Same "actual resolution" as the older 27" but with much sharper text.
I use a 48" monitor that lets me have 4 to 8 zones pretty easily, usually the bottom two get the most attention but the top comes in handy when monitoring something or keeping up on stonks.
