As an old player, the bit I always disliked was using the inbuilt site-finder with rather exacting qualities of drainage/elevation[1]/etc to find nothing matched, and then being less-exacting in stages (and in-breadth) to find the least-unmatching site.
...but then with the caveat that it took work to find similarly least-unmatching sites, because it would send you to just the one (you had to manually trawl over green-matching spots on the megamap to maybe find the others.
What would be good is a hierarchical fuzzy-matcher. Perhaps keeping a list of the top 100-or-so matches (dribbling into least-unmatched by hardcoded or user-definable metric of acceptibility) and/or when Site-Finding with initially loose parameters seeing hints that asking for higher temperatures would reduce the current sitelist from 50 to 20, while asking for low rainfall would reduce it to none!
(Ah, what I did here was change from "looks good, but don't forget..." into suggestions for game changes that are probably already covered by either Toady or potentially 3rd-parties. And someone'll point out I missed this actually existing. Ah well...)
[1] And maybe it's covered in the video, that I have yet to see, but I rather got into the cycling through elevation/slopiness/etc views to build up a 3+dimensional mental map. I hope that isn't removed. I presume like a Google Maps switch between default, terrain and photographic, there's something available here...