Because both of our families are large, and we plan to have a dance floor and people moving around, I was thinking of having wine glasses with the bases dipped in chalkboard paint (Glass for the adults, plastic for the kids), where you can write your name on the bottom in liquid chalk so that when you inevitably set the glass down, you don't lose it or mix it up with someone else's, and at the end of the night you can take the glass with you as a wedding favor. Is that tacky?
I was also considering writing the names of the guests on there myself, but I don't want to set out a glass with someone's name on it and, for whatever reason, they can't show up and their glass draws attention to it, nor do I want people putting their hands on other people's glasses to get to theirs.
The glasses would look something like this