I am currently running dual 28" 4k screens, both set to 3840 x 2160.
The right monitor I use for my shaman windowed at 2560x1440 and I have the DXForever UI installed using DX1. His UI stuff is in the middle of the screen and I have text windows going to the edge. Is it a little small? yeah a little, but it is a 28" screen not a laptop so it is not that bad.
The Left monitor is my Warrior running full screen 3840x2160 with a custom UI. I have done alot of tweeking on font size in order to get the fonts large enough to read.
I Say that all to say, PLEASE dont listen to them about lowering the resolution.
If your system will handle you playing at the 4k DO IT. The curving of rounded items and the details are soooooo nice. I am running with everything but bloom lighting on and its absolutely fantastic. The quality of the image is sooooo nice.
But, that is how I found this post. My son is running at 1920x1200 and I am attempting to find the variable that lets me know what resolution the game is at.
I tried to inline a picture of my desk with eq running but it seems not to work, here is a share to my google pic.
Picture of my desktop running eq hosted on google photos
Just my 2 cents take it for what its worth.