Making the garage door secure is #1 after that install BRIGHT motion activated flood lights. I'd separate frames from wheels and lock separately then leave one cheap,new, good looking bike pointed towards the door like it's ready to be ridden out. That's the sacrificial lamb that you rig any way you want. Loose handlebar stem, loose brake cable, etc. I've been helping a friend tune his BikesDirect $299 road bike, that would be a good choice.

Most important thing is making the door secure, once they can break in and harvest once they'll be back for more because they can see what else is available that they didn't have the time to get and they can bring the long bolt cutters.