Until I purchased my own Cape Cod home in 2000, my children and I rented cottages for two weeks every summer for 12 years. We really settled in for those wonderful vacation days. The first thing I did was to push aside decorative items that were vulnerable to damage from four young children. I moved a chair or two to reflect the way we were using the rooms during our down time after the beach. In every case, I carefully replaced everything just as it was when we found it. My goal was to make it personal but not permanent.
Our friends at Houzz.com have great ideas on how to tweak a rental cottage to make it more like "home". While not all the advice is something I would have done -- bothering to bring a framed photo of our family in an already filled-to-the-gills car, others, like taking a quick phone photo of the layout so you remember exactly where everything was when you took possession, you'll find something you can use on your Cape Cod vacation.
You might also like:
Planning a Trip to Cape Cod? Start with "Street View".