Hello!

I am hoping to get some thoughts on bridesmaid dresses for a relaxed, outdoor ceremony (hopefully!) on October 4th. I am in the super early stages of planning (waiting to go public with ideas until we know for sure we are financially able to buy a home within a year). I have been thinking about how to make finding a BM dress easy and convenient with our colors being pale pink, gray, black, and white. I plan on asking my twin sister, a close family friend who is like a sister, and my 2 FSILs to stand with me.
Which option do you like best ease and colorwise?
1) Any cocktaillength black dress
2) Any cocktaillength dress of any shade from a gray paint chip
3) Any cocktail length black or gray dress
I know that the little black dress option is the most convenient, but might the black be too contrasting against the vibrant, colorful nature? All thoughts and suggestions are welcome!
ETA clarity with punctuation -- was on phone