When you are the parent of a small child, whether that child is a peaceful cooperative angel or whether that child is some sort of mischievous imp, your kid won't be any less destructive in someone else's house than they are in your house.
1. Lockdown the bedroom. Pick a bedroom for the toddler carefully. We chose the smallest bedroom with one window. That means that worst case scenario, only one roman shade to pay for. I also took out the tv, both lamps, alarm clock, framed art over the bed, and turned the dresser so he couldn't open the drawers. It might also be a good choice to remove the dresser altogether as my kid tried his darndest to completely destroy it. Luckily I'm pretty sure it's not an antique handed down from French royalty or something.
2. Bring toys, small quiet ones, new ones are best. You leave your house and drive to your vacation spot and after you've unloaded the car and you're hot and sweaty and ready for your first umbrella drink on the deck, your kids are staring at you saying, "I'm bored". Yeah, been there, done that. Solution: "Hey, go check out this cool new thing!" If you present your toddler (and/or older kids) with something they haven't seen before, you'll probably get enough time to suck down half of a cool beverage before they get tired again. Kids need stuff to do and although you may be happy to watch birds or boats go by, this just won't cut it for them. Legos, rubber figurines, trucks, barbies, whatever floats your kids' boat, bring it. But don't bring anything big or you'll be annoyed that you have to do just as much cleanup on vacation as you did at home.
3. Don't forget that your kid has to eat! I know your rental said that the house was fully stocked, but face it, the realtor and homeowner may not realize that your mind includes sippy cups and plastic plates. It's no big deal to throw a few plates, bowls, cups and tiny silverware into a bag and bring it along. I went to Ikea and picked up a fresh stock of this stuff on the supercheap. I also grabbed a pack of Solo cups/tops/straws at Target for on-the-go beverages. Not a green solution, but very convenient.
4. Have food rules. Now I have fond memories of my kinda-grandmom having firm rules about food in the tv room at their vacation house. And when I was 12, I thought it was superstrict, but not having to vacuum goldfish out of the carpet and couches everyday is really nice. I may need to institute this rule at home because it really was nice not having cups and bowls all over the house.
5. If it's broken, then fix it. Properly! Face it, your kid might break something. It happens, a lot. If it happens on vacation, then you should consider whether you can fix it. Last year Chris ripped the upper rack of the fancy dishwasher and broke some plastic part. I ordered a new part and installed it myself for $36 (probably a lot cheaper than a local repair guy or reporting it to the realtor). This year Chris tried to destroy a dresser and I attempted to do a repair and it turned out bad. If you will be doing a repair, do some research on the internet or visit the hardware store to make sure you're using the right kind of glue, screws, etc. And that you have the proper tools. If something is broken and you aren't able to properly repair it, then be sure to tell the realtor. This is what security deposits are for.
6. Try to relax. Vacation is supposed to be a fun and happy time for everyone, but it's easy for things to get stressful for parents. If your kid seems to be living on donuts for breakfast and ketchup for dinner, just try to remember that this is but a week in their lives and that you can get back to normal when you're home. And remember, next year your toddler won't be a toddler anymore.
Oh and as a safety reminder - bring along some childproofing equipment (gates, cabinet locks, outlet covers, etc). When cleaning our place, my dad found that Chris had done this to a bunch of outlets behind the dining table: