I remember being very inspired by the PS2 Ratchet & Clank games. They did IMO a very good job of creating scenery and hardware that balanced scale with detail in a way that would transfer brilliantly to tabletop scenery.
Resident Evil 4 had a lot of seriously inspiring environments for me in terms of detail and texture. The entire Silent Hill series of the PSX-PS2 eras (1-4, plus the PS2 version of Origins/Zero) as well.
More recently...
I'd totally agree about Deus Ex: Human Revolution. That game has some really beautiful design work (and yes, I would love me some tabletop boxguards).
There's a F2P game called Hawken which has "pretty/ugly" mechs that are great painting references for "gritty" mecha or AFVs.
Tempting to say Mass Effect, but that's a bit cheating IMO since Mass Effect's hardware designs are so very, VERY Syd Mead inspired that you might as well just cut out the middleman and reference Syd Mead.
Spec Ops: The Line's sand-flooded city does a bang-up job of feeling dream-like surreal yet real at the same time. As it should, since the game is basically a re-imagining of Apocalypse Now (in turn a re-imagining of Heart of Darkness)
Could probably learn a lot by looking at how XCOM's (the remake) maps are made to both look real and operate on a grid system almost directly translatable to a tabletop.
The principles of good "grey box" design for video games are pretty much the same as with good tabletop layouts. The video gaming industry has all but made a formal academic discipline of it, so reading about video game level design or deconstructing the maps of the video games you play, regardless of subject or genre, could potentially improve one's own tabletop layouts a lot.