Board formed concrete walls is what first came to mind to me. It is more expensive because of extra labor. Do you have example of what you are looking for?

http://mattrisinger.com/craftsmanship-of-concrete-board-formed-walls/

http://mattrisinger.com/craftsmanship-in-concrete2/

http://www.lifeofanarchitect.com/board-formed-concrete/

Here's an example of the panel - basically it's a 4x8 sheet with foil / Formica / something that looks like woodgrain on it.

http://www.roseburg.com/ProductGroup/duramine/

I've seen this done in a commercial building:

Modern Living Room · More Info

Modern Peninsula Estate · More Info

Obviously, you can also do cabinet grade plywood and finish it nicely - which is surely an option - in about 5/8" I would think.

I don't want to pour / form concrete - it's messy and honestly - I am thinking that warming up the space with wood (look) is a better answer.

Too much Fixer Upper has be looking at shiplap too.... raw / unfinished.

Here's a rendering of the interior of my project:

We will be using some glass panels and maybe even polycarbonate - but need something to hide plumbing and electrical (although it might be cool to see some of that exposed too.... and I have seen walls lighted from the inside using the polycarbonate, too.)

Stone? Lit from behind? Or Neolith?

If you find something cool, please come back and let us know the details. I have a modern home and this looks very interesting for the future space we are looking at once phase 1 & 2 are done.

Cultured stone panels, stock or custom made, are another possibility. But not if you want to contrast the rough concrete with some super smooth surface.

Here's a wall of cultured stone panels I put in one home. (When selling it, it was sad to see how many prospects wanted to know how they could remove it to return to the beauteous drywall behind it.)

I have about 4500 sq ft of interior wall I will have to do. Large format tile or a sintered product like Neolith has an interesting appeal - but.... it needs to be mounted on something, or if you get the thicker stuff it's pricey per sq foot.

My architect sent me some pics - I'll upload and share them here and see what you think - I truly believe that we will need a wood or wood look product in order to warm things up and be somewhat cost effective - but we're also discussed some backlit plexiglass / colored accent areas, too - it's so easy / cool to do that these days with LEDs. My house would look like the Partridge Family bus!

Stay tuned.

Cork?

Yeah - cork might be VERY cool- and help with sound absorption - something that I will need to manage! Here's some ideas... I am wondering if I could use a strip cork FLOORING, horizontally on the wall....

http://www.dwell.com/houses-we-love/article/six-concrete-boxes-make-jaw-dropping-marthas-vineyard-home#11

http://www.wsj.com/articles/SB10001424052748703956904576287164203018794

I put panels of bamboo on the back wall of my bedroom wall in my condo. Here's a picture. Maybe something like that would work?

cpartist - that is lovely - that's precisely what I think the space needs. Is it anywhere NEAR affordable?

Yes it is. I'm trying to remember, but I think it was thin panels that they glued to a heavier substrate. Or maybe it was heavier panels? It was 7 years ago. Panels

I am wondering if I could use a strip cork FLOORING, horizontally on the wall...

Yes, most any flooring actually. Coliln and Justin do just that in a recent reno of a traditional cottage.

Looked a little at the strip flooring - that's a good idea, too - especially as it will provide some thickness / stiffness.

Thanks for all the great ideas - I think this is the right path!

I just watched episode one of the most recent season of "Grand Designs" from the UK on YouTube. It was fascinating and the modern design might interest you. I can't find s link to the show on my phone, but here's an article about the house. I think all the walls are clad in large porcelain tile. It's stunning. And extremely expensive, of course.

http://www.express.co.uk/showbiz/tv-radio/604149/Grand-Designs-Kevin-McCloud-Clinton-Dall-Sussex

benjesbride wants me in the poorhouse. ;-) The issue with tiles is that you also have to have something upon which to mount THEM - so it's 2 materials. It would be an awesome look - and they do make those giant sheets in about 1/8" thick - to be a little more "cost effective" ha! but between specialized labor and the substrate - I'd need to sell a kidney.

I am looking for "one and done"...