Darker grey curtains may either trick the eye into thinking the walls are also grey or they may draw all the attention and the contrast may be too great. I think colorful curtains may help the eye see the walls as grey!

Edgecomb Gray is a light-ish color since it's LRV is 63, and is a "green-gray" that can read as an off-white or a putty color. I've used this color when I wanted a neutral other than beige and didn't want to commit to a gray. It does work as a neutral backdrop for most colors, so you could just bring in colors in your desired palette through your decor. Also, it does look really great with lots of white to freshen it up. But since you said said you were hoping for a more of gray, I'm wondering if you wanted a more "modern" or cool gray with less of the warm undertones? If that's the case, then a new paint color might be needed.

I think darker curtains will just make it read as white. Like Jess said, best bet is to put REAL white in the room through curtains perhaps, trim,
. Also, playing with the subtle color temperatures of your furnishings in comparison to the walls will make them more distinctive.