This year, I left everything related to work at home. I really needed two weeks of not doing any scientific work, but just go swimming and biking and reading some of the volumes from my "to-read-shelf." And there is one thing that really supported this decision: We didn't have Internet connection in our vacation appartment. And there was even no wireless connection via smartphone possible in the entire village. Great! My "out-of-office message" worked quite well, I wasn't able to read or answer e-mail message for two weeks. And two weeks is probably a perfect duration for vacation from work and from the Internet: A lot of requests to read this and decide that had taken care of themselves when I returned.
I really can recommend vacations from the Internet -- there is no sense in doing work-related things during vacation. It's better to come back to a not so clean desk with a refreshed mind than coming back to a clean desk still feeling somewhat exhausted.