I used to think the same way regarding having a sign to tell our players which table they were assigned. It was a train wreck; despite the signs. I ended up getting creative about it, and got speedcloth in 4 different colors. After refelting the tables, I could just assign people to "the green table" or "the blue table". It made life so much easier.
I do this now at both of the locations I host multi-table games.