You can always add some white paint to it to make it lighter if it's too dark for your taste. Just make sure the paints are the same type, and mix it until it's like a creamy soup. I just did that with 3 paints as the one I went with turned out to be too dark. It came out beautifully.

If you don't want to do that, go to the website of a paint company and go through their paint selection. Most have a feature where you can upload your own pictures and 'paint' them, or you can use their stock photos. With that feature, you can customize the paint you making it darker or lighter, brighter or less bright, and add more of the two colors it's made of. I've found doing this very helpful in deciding what colors to go with. Plus, if you like color, it's a lot of fun.

Yes greys can go cool or warm,. My suggestion is to get quite a few color cards to compare. Also your outside lighting will affect the color depending on which way the windows face. Look at your samples at different times of the day and night....than you may want to buy a few quarts to try on the wall first before you make a final decision.

My latest favorite is BM Mineral Ice...

Edgecomb gray

Stonington Gray is a pretty "true" light gray. Coventry Gray is also nice, but is a tad on the darker side. Definitely put up samples before making the final decision!