This is relevant on the laptops or devices with smaller screens mostly, 1080p(24in) monitors are fairly common those days which gives more than enough screen estate to fit at least 2 side by side windows, ~100 char width text is recommended width for text reading.

And as for linux distro with a good GUI I would suggest looking into Elementary OS which is a ubuntu based and UX oriented. I used it on a daily basis for about 6 months and had good experience (not excellent though, it has some issues but what doesn't?)