Here is our list of things we do before we leave the house on vacation.
Most of the irregular items are lessons learned:

Make sure all toilets are flushed

Make sure all doors are locked

Make sure all windows are locked

Make sure garage door is down (you don't want to know)

Make sure all garbage disposals have been run

Make sure all plants are thoroughly watered

Stop mail

Stop newspaper

Unplug all electronics (TVs, computers)

Make sure TiVO is on and records favorite shows

Make sure washing machine is empty

Let neighbors know we'll be out of town

Make sure all garbage cans in kitchen are empty

Make sure dishwasher is empty or clean

Make sure refrigerator(s) and freezer(s) doors are closed

Make sure fence gates are closed

Make sure all lights are off except one

Make sure alarm clocks are off

Make sure the garage door is down as we drive away

Double check the garage door is down as we drive away

Have the boys check the garage door is down as we drive away
After our trip to Florida at Christmas last year, we came home and our garage door was up. After a terrifying search through the house, we realized no one had been in the house or garage. So for ten days the garage door was wide open and the door into the house wasn't locked. We assume there was something blocking the door when we left and we didn't notice that after the door started to go down that it went back up. We were lucky. It also confirms we live in a safe neighborhood. We did spend the next several weeks trapping mice that had come in for some warmth.

Triple check the garage door is down

Drive around the block and come back to be sure the garage door is down

Call neighbor during trip to verify the garage door is down

Place a webcam outside so we can check at anytime the garage door is down
...you get the picture. We are getting close now...maybe I should start checking now that the garage door is down.