Dark paint color in the whole room or accent wall?

How much light does it get? Do you want it to be dark and moody? Or Are you aiming for a focal point? What's your decor goal when this is all done?

Covering the dark red will be easy -- but you have to use Kilz or something like it to prime the walls. You will want to do this on every wall so the new paint is all the same and no splotchiness. if you don't then the red will eventually bleed through to whatever color (even a dark gray) and it will look bad.

If you choose lighter colors for the other three walls, consider diluting the darker paint with white ---- it will keep the shade but make it lighter. If you go this way, plan on measuring out how much white you add so you can recreate it in case you run out of paint later.

I am obsessed with those blues right now. I hate the color blue….yet that is my current accent color in my home. I have SW Gracious Greige on most of my walls, and that blue is in one room.  My blue room has 4 big windows and can be seen from the foyer, family and dining room. We painted all 4 walls. Like you there isn't a TON of wall due to windows, French doors and openings.  Enjoy that pop of color.

I’d paint an accent wall first. Love the sample above. If you like it you’re good. If it’s not enough, you can go for the whole room. I would live with the accent wall long enough to make a truly informed decision with different times of the day and also how it will be with less daylight or cloudy weather as we move closer to fall and winter. I would really NOT want to have to paint over dark walls twice in such a short time period.

I'd prime all the red and then paint your accent wall the color of your choosing. I think you will know fairly quickly if you want to paint the other walls the same dark color or something lighter. You could also go just one or two shades lighter. It likely won't be that noticeable that it's a different shade, but will still be harmonious.

I painted our bedroom a light beige when we first moved in. It was a horrible dark green. I used Behr Ultra because it has a built in primer. It covered the dark green with one coat.

I would paint the whole room the same color, something neutral, not teal. You can add teal accents in curtains, rug or something easily changed out if you get tired of it. Depending on the size of the room an accent wall can make the room feel smaller. Depending on the size of the room I might try a little darker than the Revere Pewter, just
be careful to use some with the same base tone, (blue gray, pink gray, yellow gray), the tone can make a huge difference.

Just wanted to chime in here to say that when I was looking for teal curtains for my lake cabin bedroom, they were nearly impossible to find! And it’s a difficult color to get the right shade. It took me months before I finally found some I could live with. I also had a hard time finding bedding in colors that would coordinate. I normally lean toward choosing neutral paint colors but I was outvoted by the other 2/3 of the family.

In hindsight I wish I would have picked the bedding and curtains first and THEN picked a paint color that coordinated with them since I would have way more choices going in the other direction.