We have used our vouchers when we checked in. However, sometimes they will ask you to come back the next day, with the activated AP. Otherwise they will charge you the full rate.
Our APs were made out of a kevlar type paper. Very strong and tough. It actually held up better than the plastic credit card type hopper passed we had before. I put about 24 days on my AP this year and it just started getting a crease on it. Also, don't put them near any electronics...cell phone, etc. It really can mess up the magnetic strip on the back!!