Some of you are probably trying to plan your vacation around the project you're on. Good luck. Every time I did that, the project was in some crucial place and my bosses asked me to consider changing my vacation.
Don't give in to their pleading. If the project is in good shape, you being away for a week (or even two) is not going to hurt the project. If the project is hopeless, you being away for a week or two can't hurt the project any more. It might even help, because the project can't depend on you rescuing the project. If the project is teetering on the edge of being healthy, you can make it even healthier when you return, refreshed by your time off.
Vacations help you become better at your job. When you spend an entire week (or gasp, two weeks!) away, your subconscious can work on the problems at work. Your conscious mind is working on the issues of your vacation. When I took bicycling vacations, the biggest problems were: when did we stop for lunch and refill our water bottles, and where to go for dinner. Now that I take lie-in-the-sun vacations, our biggest problems are which beach to go to, and where to go for dinner. (Hey, dinner's important on vacation!)
Inevitably, when I was a developer, I would come back from vacation all fired up, with a new idea for the design or architecture of the area I was developing. When I was a tester, I came back with at least four new ideas for testing and automation. As a project manager, I knew how to replan the project. As a manager, I had new tactics for the strategies we were trying to implement. No matter what my job was, I was relaxed, for at least a day or two 🙂
So, if your company wants to get that vacation time off the books, take it. If you haven't had a week off in six months, take vacation. You don't have to go away; you can stay home and clean up, read a racy novel, investigate all the Starbucks' with a 20-mile radius, take the kids to a water park (hey, they don't have to be your kids, or even under the age of 40), surf the web and read other people's weblogs, whatever. The key is to not think directly about your day job. Think about something else. Vacate.
When you return to work refreshed, with a bunch of new ideas, you'll understand why everyone other than USA companies takes more than two weeks of vacation. (There was a story on NBC two nights ago, but I can't find it. If anyone else knows the link, send it to me, and I'll insert it.)