The tickets you get from the various ticket brokers are paper with a plastic type coating for durability. We used this type on our last trip and they were fine, no problems. I kept them in a ziplock snack bag to keep them together and safe. The first time we went to Disney we had the credit card type that were our room key/park tickets all in one.
I have read elsewhere on these boards that if you purchase your tickets in advance and are then staying on property that you can have your tickets transfered on to your room key. That is what we are planning on doing this trip. If it doesn't work then I'll just keep them in the ziplock bag like last time.