I don't have any experience with Shale, but I just googled it and it looks like a fairly light color. You could try it at 25%, maybe? I am all for non-white ceilings; however, my honest opinion is that I see a lot of little white "things" up there on that ceiling (can't tell what they all are -- some are vents, others might be smoke detectors or something?) that might look like random white polka dots on a non-white ceiling. Do you know what I mean? I'm talking about the pic of the second story ceiling. So I guess what I'm saying is if you go with a color other than white, I'd suggest keeping it as light as possible so those little items aren't too conspicuous. Unless they can all be painted, too?

pictures would help, there are lots of posts on how to do it. Just search on google, gardenweb, how to upload pictures and I'm sure you will find something We just painted our dr blue and I didn't like... not to say you won't but it just felt cold to me, that said, I have seen tons of pretty blue dining rooms:) we are having to repaint ours;( Anyhow, you can look in the blue gallery for paint ideas and or google blue dining rooms. Here is a link that might be useful: blue gallery

Im really looking for guidelines- if there are any. IE should I look at a specific 'shape' of chair to compliment a 'barrel/oval shape table', (squared, rounded, etc), is a pop of color 'smart' ? chairs are so $$, what's the thinking on upholstery - leather, velvet craze, other material. if table is glass/metal is the 'convention' to stick with metallic legs, or does it matter ? for context: the style of the room/house is what I would call contemporary/modern - but defl'y not minimalist. The floors are 'wood look' tile - black with 'grayish' veins, the walls are dark grey, trim white. I just ordered table - italian, matte black glass top a 'golden' metal cage pedestal. any / all tips to get started on the hunt / help me narrow down appreciated.

Sounds like a fireplace re-do might be a longer-term fix. In the meantime, I'd paint the mantle a dark brown, a similar colour to your end tables. It's not trim and shouldn't be white. It pops out too much in the white colour. Another idea that doesn't involve any ripping-out is to go right over the existing mantle using a mantle slipcover in wood. Here's one of many how-to's on the internet. If you stained your brick as well, you could have a whole new look. https://www.fwmadebycarli.com/2011/01/making-of-slip-covered-mantel.html