Set your air conditioner at 85 deg or so. Your bill should only be $20/m or around there. Leave your refrigerator on with some bottled water or cans of pop for the cold to zero in on. It's harder on them if you turn it off. Turn off ice maker. Turn off all water. Turn off water heater. Notify local police that you will be leaving for months so they can check the house occasionally. Most areas do this service. Cancel your newspaper.
The very best thing you could do is to have someone you can trust to come in once a month and run the dishwasher, garbage disposal, showers to keep the traps full, sinks for same reason. Perhaps your realtor could recommend someone.