The auto reply vacation message is a great thing. It can alleviate the wonder of knowing whether you are out of town or just ignoring your clients when you don’t answer their message. It is also probably the last thing you think about upon your return from Tahiti. When you turn it on as you are boarding the plane, put a reminder into your calendar to remind yourself to turn it off.
The same rule applies to the voice mail message announcing your vacation plans. Change it when you get back!