I lalso like sort of a light sage green - there is another greenish gray (like Easter Egg dyes at the end of the dying session) that blends with a lot of colors. Actually, I've learned that I can use almost any drabbed medium tone thread with most fabrics.
I have a large "stash" of thread - so I'm trying
I used to think my thread had to match very closely for sewing seams. As long as the thread does not show from the front, it does not matter.
I do get indecisive when I am hand sewing white - or a very light color - to black or a very dark color.
It's been a while - but I think I used a light color thread on the light side, and a dark color on the dark side.
I really agonize about what color thread to use when I am hand piecing a light and dark fabric together.