Put a paging alarm with a proximity sensor on at least one bike, park close together. The other is at least partially-protected then. Chain them together with the kryptonite cable, and roadlok each of them. Make the thieves work for it.
Like others said, try to park indoors if possible. If not, park where you can see it from a window. Pay the hotel a little extra to park in a lighted area or next to their office if it's staffed all the time. A little preparation goes a long way.
If the thieves really want it, they'll get it; just don't make it easy for them.