Quoted from starfighter:2. A PA announcement every hour or so mentioning the different show room locations.
Agree in theory, but I've yet to hear a PA in any hotel or convention center that is understandable. Even when it's audible, words get lost in the echo & din of a show.
Love your idea for the tall signpost, though. I bet at least half the attendees this year didn't know the Spanish/auction/overflow room existed.