Leaving the house empty, whether it's for a weekend or a month, requires careful consideration — for the living beings in your home, for the things in your house, and for the house itself. Here are some ways we prepare:
Pet behavior. Of course you've made arrangements for your pets— someone to come over and take care of them while you're gone, or someone to take them into their own family for a while. When you leave the animals at home with someone looking in on them, it's important to consider that their behavior won't necessarily be the same as when they're in your presence. For instance, we have to put our cat bowls on the counter when we're gone so our dog doesn't eat their food. And if we want to make sure Isabelle, our adopted Doberman, doesn't make herself at home on our chair cushions (something she wouldn't dare do with Mommy and Daddy home), we need to prop them up against the backs of their chairs.
Make plant-care easy. If you're going away for more than a week or so, your plants will likely also need TLC. Make watering the plants easy for the people who are helping you care for the pets and house by putting the plants all in one spot. A sink or bathtub that gets good light are ideal options because the water is right there and any drainage won't be a problem. Don't forget plants that you've placed outdoors that may need to be watered. Wilted mums on the front porch aren't so nice to come home to.
Unplug what you can. No need to keep the Kitchenaid or the TV plugged in. Standby power, though not an issue with every item, can use electricity and even pose an unnecessary fire hazard. We just go around and unplug what we can, just in case. My husband even turns off our tank-less water heater. A possible exception is a light you leave on to make it appear that someone is home. For this, you could also consider a timer that switches the light on at a certain time each day.
Empty the trash, fridge, dishwasher, washer, etc. In the bustle of getting packed and everything else that goes along with preparing for a trip, it's easy to forget the dishes that haven't been run, the last load of wash you had going, or the yogurt in the fridge. Check everything and deal with anything that might get funky in your absence. Prop open even a slightly damp dishwasher with a wooden spoon so that mildew doesn't grow, for instance.
Don't turn off that thermostat. Turning off the heat or A/C might seem like a no-brainer, but think carefully about the weather first. Even if you don't have animals to keep comfortable, it's good to keep your home and the items in it at a fairly moderate temperature. A lot of this has to do with the moisture in the air and how it causes wood to expand and contract. Air conditioning also dries out humid air — something that's extremely important to consider if you'll be gone for long. We have friends who left their Georgia home for the entire summer with the A/C off and came home to a film of mold covering everything. What a nightmare.
Hide valuables. No one likes to think of the unthinkable — of burglars in your home. But it happens. I don't have any jewelry that's very valuable monetarily (which should probably be kept in a safe deposit box or the like when you're gone), but I have plenty that is very valuable sentimentally. I hide it. I won't tell you where.
What do you do to get your home ready when you're going to be gone?