This is one reason why I don't like 4k monitors. The pixel density is just awkward. If I use 1 point = 1 pixel, then the UI is way too small. If I run at 1:2, the UI is too big and the screen is effectively a "retina 1080p". And if I try 1:1.5 then the smoothing artifacts are too visible.
I ended up solving this with a 5k display at 1:1.6. The smoothing artifacts are below my threshold of perception and all looks nice and smooth, while still having a 3200x1800 usable resolution. Downside: cost.
Better yet: HP’s Z27q display. It’s 27 inches and 5K, which is “Retina” to 2560x1440. And I’ve got two of ‘em (…and a 6-head GPU to accommodate their MST cables).
I just wish there was a 16:10 aspect ratio option.
UPDATE: The "real" 5K HP Z27q model (with 30-bit color and 5120x2880 pixels) was released around 2012-2013 and was discontinued by 2016, which is a shame because it's such an amazing monitor: I imagine they discontinued it because 5K operation requires 2 separate and hefty DP1.2 cables in MST mode, which (at the time) the majority of computers just couldn't handle (I don't think Apple Macs can use it at all), and Windows' support for high-DPI was awful-to-mediocre until Windows 10 came out in 2015 - but they've been fantastic for me. Oh, and it was bloody expensive: each one new was about $1500-2000 IIRC.
It seems HP has re-released the Z27q... but in-name-only: the current model is called the "Z27q G3" but it's now just a mid-tier 27-inch 2560x1440 IPS display with no special features beyond DisplayPort 1.4 in-and-out ( https://www.hp.com/us-en/shop/pdp/hp-z27q-g3-qhd-display ). Originally the "q" in Z27q was for "quad" because the 5K (5120x2880) resolution really was 4x 1280x720 (the OG "high def" before 1920x1080 took-over), but now the "q" stands for "QHD" which doesn't mean Quad-HD dimensions, but just 4x the pixels (which isn't impressive at all: as pixel-count increases squared as length increases). Grumble.
Apple still has their own LG-made 5K monitors but they don't play-nice with Windows, and it's even worse with Apple's horrendously priced 6K monitor - but other than that, there's still very few options left for people wanting or needing a large desktop workspace beyond getting a 40-inch 4K display and running it in 96dpi mode.
I ended up solving this with a 5k display at 1:1.6. The smoothing artifacts are below my threshold of perception and all looks nice and smooth, while still having a 3200x1800 usable resolution. Downside: cost.