I know that traditionally the MOB selects her dress 1st, and communicates the general style, color and length details to the groom's mother at which point she can then select her dress.
I would assume that the groom's mother should select a different color dress than the MOB selected. Is the grooms mother supposed to select a dress of approximately the same length? What's the ettiquite on dress lengths for MOB&Gs?
Any other attire details I missed?