New PC for 5 accounts on WoW

[MiRai]

I was able to watch a couple of your vids on YouTube, and I was wondering what size monitor are you using?

I currently use a 4K 42" UHD420 display.

Would this monitor work?
LG 34UM61-P 34" Class UltraWide Full HD IPS Monitor
2560 x 1080 Resolution75Hz Refresh RateFreeSync Technology5ms Response Time21:9 Aspect Ratio

In my opinion, I think 1080p stops looking acceptable after ~27" where the pixels reach the point where they can become noticeable, which can affects image crispness.

I would like to setup like you had the 4 minions on the bottom. I dont need 4k viewing, I just want the main toon to have a decent size so I see what's going on main with a little access to see what the others are doing.
Would two of these be significantly better than one larger monitor?

It's hard to say because it's subjective—some people swear by using multiple displays—but after switching to a single large display, I certainly enjoy using a single large display for everything.