M.D.
We don't do a big family theme. But I volunteer in the classroom for my kid's Halloween party every year, and I dress up to go to school. It's fun. My kids typically do coordinate, but at this age it's mostly because younger thinks everything older does is cool, and so he copies him (older doesn't mind-yet-).
I'm not creative, so I go the costume store and just look for a female adult costume that I'm not embarrassed to wear in front of elementary age kids. This year, it's Cleopatra.