What colour of Curtains to go with

You could use a pattern on your curtains. I'd suggest light background with a grey geometric pattern. Then you can still use other patterns and pops of your favorite color to accent, such as yellow, aqua, teal or whatever you choose. I find when I use colors that I wear and feel good in, I'm happier with my decorating.

Since everything you described is pretty neutral, I would go with a pop of color.

White , gray, or dark gray would go with it. It depends on what you would like to accent the most. To bring out the eye popper or focal point on the fireplace, pull a color from it to match the drapes.

You have all neutrals and have yet to pick your accent color. What ever you choose, include it in pillows, candles, area rug etc. Pink, lavender, salmon, red area all possibilities.

With the colors you have, I would say gray, white, black are your best bets. You could go with a red, purple, or blue in if you wanted to have some color to stand out.

If it is a small room; curtains a slightly brighter/and/or darker shade of the wall color. You don't want to visually cut your room up too much.

I would go with a red/burgundy type color. Then add that color in other things in the room. Pictures, throws, pillows, etc.

I would go with a darker gray than the walls, or white. then bring color in with accessories.