I like the grey, it really brings out the beautiful wood tones...

ditto dcer. Plus, it just looks "cool".

jamieson is right on ... if that red fabric was in a teal/turquoise, then you've hit the late-60's aesthetic on the nose. I know of many office suites that STILL have that original furniture in orange, teal or brown. Sorry, grey is too contemporary. Just depends on whether you're going for retro, or updated retro.

I think black leather or houndstooth would be a great contrast; but I voted for brown leather. I like leather for durability and it is easy to clean.

dcer nailed it!

Like the grey best -

Love Jamieson's point about 1950's/early 60's decorating colors. The ones I remember most vividly are tangerine and turquoise. What would I buy at the moment? Gray or turquoise.

If you went to the effort of sourcing sustainable woods, why not choose sustainable fabrics. Maharam has some great vintage options, that do not contain heavy metals in the dyes, contain biodegradable or recycled fibers, and look super appropriate for your lovely pieces. You can search on multiple environmental characteristics, such as Rapidly Renewable, and Greenguard Certified, this fabric is both:

Boucle and high texture fabrics always work well against clean wood tones.

Jamieson, who can argue with your reasoning? :>)

You don't have to watch TV to see that the grey rocks!