I use a regular disc lock that you can get any where. I also use a large "On Guard" chain.
I think what you should try to do is make it difficult for the thief. I put the disc lock on the back side of the disc or where it's hardest to reach instead of in front on the top within easy reach. And when with others we daisy chain the bikes together with the chains.
When at hotels I always ask where the video cameras are and if they won't let me park under the check in entry then I put it where the cameras are looking.
Wood is right about picking a bike up. When my clutch cable broke at Little Sturgis 4 of us picked it up and put it in the back of a pickup in just a few seconds.
