The typical desk job in the States starts you off with two weeks of vacation per year, plus some standard company holidays. You gradually work your way up until a trillion years later, when you get four or even five weeks off per year.
Law firms start associates off with four weeks per year, plus firm holidays, but it's all for show. No one really takes all four weeks off, and chances are pretty good that you'll end up working on a fair number of the holidays and weekends, as well.
Then I left New York firm life for Swiss NGO life. When I first learned that I would get five weeks off, plus about two weeks of Swiss holidays, I couldn't imagine how I would use that much vacation up each year. Weekends and holidays? They were mine, as well. The first year I was there, I ended up with a few days left over, but after that, I used up all of my vacation days, and by the end of my time as an expat, I was finding it difficult to stretch my days off to fit my travels. My friends and I wondered, "How did we ever get by on less than seven weeks off per year?"
And then I moved back to the States. I get three weeks off, plus twelve company holidays, for over five weeks off total, which is quite generous by American standards, but still not quite the same as the Swiss seven. I worried that I would find it difficult to adjust back to the American way. As it turns out, I've been back in the States for over ten months, and have only taken two vacation days. In fact, by the time I hit my one year move-a-versary, I'll only have taken seven out of my fifteen vacation days. How things change...
On the other hand, that number is quite deceptive, because I'll also have spent thirteen days working from our offices in London, Zurich, and New York (to avoid taking vacation time while traveling), taken all twelve of the company holidays, and spent several days at company or department off-sites (wine blending, eating, doing pub trivia, skiing, going to the beach, and so on).
I'm not really sure which system works better for me yet, but at least I can say that, contrary to expectations, I don't feel vacation-deprived.