Depending on how large your display is, it may either not be HiDPI at all or it may require fractional scaling which is currently unsupported. You might find this article interesting: https://medium.com/elementaryos/hidpi-is-more-important-than-4k-b1b9bb110b43
That’s awesome to hear you’re using elementary OS on a bunch of machines! You can find our current tutorial here and you can be sure that we’re working on a set of improvements to these docs to sync with the changes that are coming in Juno. We’ve also been putting some work into making sure the documentation at Valadoc.org has code examples so if you…
At the moment we only support integer scaling and all displays must use the same scale. We won’t be able to have non-integer scaling or multiple scales until we get to Wayland
I’ve been thinking about trying to pick up an ultra wide. I haven’t heard any reports about them at all. What kind of issues are you facing?