Is it okay to mix colors of chairs within a room?

Yes - as long as all efforts have been made to have only one color in the room and we have run out of chairs

It always helps to look ahead so that we dont have to undo a set later based on the color of chairs used. For instance, if the Ballroom is being used currently with 100 chairs and you are setting up the V-Berg, Hussey, and Michigan each with 100 burgundy chairs and then the Ballroom gets out and you need another 200 chairs in there.... you would have to unset a room you already set. This is what I mean by looking ahead to avoid having to re-do work.