Commit to a date, and time. No one likes being surprised with last minute guests, even if they say they do:) If you get an invitation, commit to the date and make sure your hosts know when you'll be arriving. Many cabins/cottages are on islands or in remote areas with spotty cell phone reception. You don't want to inconvenience your hosts before the weekend even starts by running an hour late.
Bring food! And more food! And alcohol! Bring way more food than you imagine you could possibly eat. I often find myself in the grocery store, wondering if we really need five types of cheese for a planned charcuterie board. The answer is yes. Plan meals to make for your family and your hosts, and bring along everything you need to execute them. Don't assume there will be olive oil, or mushrooms, or flour, or even salt. Bring it all. I typically like to measure out the amounts needed for baking, so as not to bring too much. Which leads me to...
Don't bring too much. ha. This point may seem to contradict the previous one, but when bringing food and supplies, be mindful of space. Many cabins will have small refrigerators and limited cabinet space. I try to bring dried goods that don't require refrigeration, along with a big cooler packed with ice. That way our food can last longer if it doesn't quite fit in a small fridge.
Bring towels, sheets, sweaters, and rain gear. Ask your host about sleeping arrangements prior to your visit, and offer to bring sheets, blankets, or even an air mattress. Don't ask about towels - just bring them. At the lake people tend to go through multiple towels per day thanks to sand, swimming, and outdoor activities, and lots of cabins don't have laundry facilities. Leaving your hosts with mounds of wet towels at the end of a weekend is not a good way to leave.
Think about a hostess gift or something for their kids. Gifts for a cottage tend to be easier than gifts for a primary home. People are quite particular about their house style and may not appreciate your choice of gift, whereas at a cottage there is typically a more casual 'shabby-chic' vibe. I don't know many cabin owners who would object to another throw blanket, water toys, or beach towels - regardless of your colour choice. (Of course - you know the hosts best. If you know their place is done to the nines - splurge on a nice bottle of wine or scotch and gift that instead.)
Help with cleanup, all the time. No one wants to feel like they are running a bed and breakfast, so make sure you - and your family - help out as much as possible. Sometimes that means doing things outside your comfort zone like helping to tie up a boat. Let your guests know you don't know what you're doing - but that you are happy to learn. If your host is busy gathering wood for a fire - offer to help. It may not seem like the most relaxing weekend for you, but managing a cabin is a lot of work. The owners likely work all week and then escape to their cabin for relaxation. An extra set of hands (yours!) can go along way! A couple years back we had a friend visit us at our in-laws cottage, and he was SO helpful. He jumped at any opportunity to help, from cleaning the gutters to painting a fence to planting flowers. Our family still remembers what a great guest he was - and always asks when he's coming back.
Know when to leave. Don't overstay your welcome, and leave at your intended time. Offer to bring back garbage or recycling, and make sure all of your own stuff comes with you.
Any other tried and true suggestions for being a good guest? Enjoy your summer week-ends... they go by quickly!
p.s. - these photos of Soren are making me a little nostalgic, they were taken two years ago and the dude is turning FIVE on Sunday. Oh time.