In my wedding my bridesmaids wore a champagne color and the men wore black tuxes. So my mom decided to wear a black cocktail length dress(nothing too funeral like). We decided black for her so that she would match everyone else but not look like a bridesmaid. Keep in mind that a lot of pictures will be taken. Since my immediate family was all in the wedding, except for my mom she looked great in the pictures because she went along with everyone else.
My mother in law on the other hand chose to wear red. I had red roses as my flower. But that was the only red I used. She turned her nose up at the idea of wearing black. So in all my wedding pictures she sticks out like a sore thumb with everyone else in champagne and black. I would suggest sticking with something that will go with the rest of the wedding party vs just what you like. You want to look good for the pictures!