Since we didn't originally have family when we got married (in a JOP Office), my mom wore a beautiful long black gown to my sister's wedding(bridesmaid color for her wedding was black) and our stepmom(who I swear thinks she's our mom but isn't) wore a long beaded champagne dress(looked like a nightgown if you asked me). For our upcoming Disney VR, I'm having my Bridesmaids all wear the same dress but 3 different colors, and the BM will wear ice blue, MOH's wear baby pink, and my mom will be the MOH/MOB standing closest to me in the same dress in lavendar. My stepmom can wear whatever she wants but it better not look like a night gown.
MOG at my sister's wedding didn't follow formality at all and wore black long spandex pants, tank top and a shirt over.
As soon as I get my new computer, Ill post pix of my mom &stepmom's dresses from my sister's wedding.