Short of suing, I'm not sure what else you can do. Have you filed a claim with your homeowner's insurance?

A friend of a friend had her room ransacked at one of the Omni hotels in New Orleans (the one in the French Quarter; among the debris left behind was clear evidence that the intruders had had sex in the room). The hotel also investigated with similar results, but at least the hotel comped her room.

Unfortunately, it is very difficult to hold hotels accountable in these circumstances.