How can I do tasteful roping off of seats I do not want used?

I have rows of theater type seating and I want to block off rows of these seats. How do I do this on a shoestring budget?

Head to your craft store and select a length of ribbon or fancy cord to suit the event. A red or black faux-velvet ribbon comes to mind, and should not be expensive. If the seats have arms, you can simply tie your ribbon to those. If they dont, use a bit of tape hidden areas. Tape can be covered up with other decorations if nessecary. Of course this is all temporary.