Maroon looks really nice with gray!!

What i would do is paint the walls a grey tone (not too dark) to blend in with the other Grey things you have.
Then you could bring in ornaments in colours that will go with the Grey tones.
If you want to do the wall Warm Grey, Orange or Lime Green things might be the best choice(You could add brushed silver to the Orange)
For a Cool or Blue Grey wall you could choose Pink, Pinky-Red or Lime Green (For Cool Grey only)
If you want a technical effect you could do the wall half Warm Grey half Blue Grey. Silver or Trunslucency might go well with this.

i really hope you concider this because i think it would really set yoour room off!!!! i say dark on the walls and white trim, my suggestion for the walls is Rave Wine you can have it mixed for cheap at walmart, that color is really deep and will go very nicely with the grey you already have, do you have carpet down there???

Using Gray with Other Colors:
Light grays go with pastel shades of pink, blue, lavender, and green have a feminine quality. Darken those colors for a more masculine feel. Gray with hot pink can be a little retro. Cool a warm palette by adding gray to rich reds or golden yellows.

Gray Color Palettes:
These color palettes feature shades of gray, including very bluish grays, combined with yellow, blue, orange, and teal.

Any light blues, or a nice red with black accent: lamps ,pillows, throw rugs

dark red or maybe even a dark blue

Any jewel tone (both burgundies, above) would do well. Are you going for masculine w/the dark furniture? Navy or forest green would also go well. You could trim it with wood stained the same as the furniture.

try a light blue; with all of the dark stuff you already have you need to keep the walls light;

Shades of blue and aqua can look sensational with grays. I know because my beloved adores gray, and I prefer greens and blues.

My mom sent us this palette from Mount Vernon (George Washington's house). It *really* helped us. Duron makes paints inspired by the colors used there and in other fine homes during that time period. You'll notice a lot of grays, and a lot of other colors that look awesome with gray, too.

Good luck!

Maroon, brown, green, blue, white, black, etc. Gray is a very neutral color. It can go with almost any color and look good. The only thing I would say is to go with a medium to dark color that you like since you have dark wood furniture. Dark wood furniture has a richness to it that needs a medium to dark tone to make it look good, so no bright colors unless you use autumn colors.

Just about anything goes with grey but brown. I would go with peach or apricot but Navy Blue works well too!If you want to get Vibant use red.

wanting the masculine pub feeling---- why not go with brick red or I would go mossy green myself. texture the wall to look like suede. great look

There are some useful tips here.