When I told my boss what that I was planning a big 2 week trip out west he said 'that doesn't seem like enough time, why don't you take a month?' OK, twist my arm
Wow, he's a keeper!
I did the reverse. Told my boss the start date of my vacation, but didn't tell him how long we were going.
We're in Europe, two weeks into our motorcycle trip, and he e-mails me, "Where the hell are you?"
He assumed I was taking two weeks. I came back 32 days later.
Better to beg forgiveness than ask permission, I always say...