I believe a dream paint is worth the wait ;D I can't offer suggestions from experience, still waiting, hopefully soon Aura will be here.) Anyway, about the floors, I did what you did and it made matters worse. DH was going to install all new hardwood and I hurried to paint BR#1 ahead of him. As soon as the hardwood went down, the stain in the oak flooring reflected just enough onto the walls to give them a pinkish cast. Horrible, it was do-over. Another bedroom (master) has cream paint on lower walls and that too has taken on a pinkish cast from flooring. I have not repainted that and it drives me nuts. (It's not like that further up the wall.) Then we had our lower level family room flooring installed by our flooring guy. When he came to measure he saw me struggling with paint samples and said "Wait, it's better to do the floor first, it changes everything." So as hard as it is to paint rooms that have new floors, it's my humble .02 that's the way to go. Just cover well, be careful, watch for stray tiny splatters and wipe right away, no harm done. Actually, I found if there were any tiny splatters it was easier to let them dry and just nudge them off (gently) with my fingernail. Didn't hurt the floor.

I agree, Ben Moore Revere Pewter : ) In my living spaces, I use flat paint, in bathrooms & kitchen I use semi gloss. If you are concerned with a 3 year old child and fingerprints, consider using an eggshell finish in your living room. It's not as shiny as semi gloss, not as matte as flat. You will be able to wipe off those prints easily.

I agree with what's been said, you'll likely need a lighter gray and swatch it around the rooms. Have you considered Stonington gray BM HC-170? It's on the same strip as Revere Pewter but has a much cooler feel. It appears that your tile has a true gray tone in it, and something like Stonington might work better. I'd advise against an accent wall, it feels very 90's and most are unsuccessful. Have you thought about painting the trim that divides the upper and lower levels the same color as the wall? Instead of dividing the two, the room will feel more cohesive. Interesting architecture, good luck!

The floors are lovely. The only way to find the "right" color is keep looking at samples; look at them at night with the lights on and in the daytime with no lights and all the the day...keep looking until one color is what you want...it is a "zen" thing and then buy a sample can and paint a sample on the wall...go back to step one....we cannot tell you what color is best only what colors to try. I like BM Balboa Mist.