This is the main reason I am a contractor -- I take a LOT of time off. For my clients, it is normal for contractors to have gaps in availability. For my on-site colleagues, they know that the vacation is unpaid.
Increasingly it feels that contracting is the most straight forward way to work for an organisation. They pay X, they get Y. No messing about with broken promises and vague commitments.
I've also been able to comfortably do contracts for companies that have worked friends (who are full time employees) to the bone. If they want a 60 hour week from me, they have to pay me 50% more.
Also, some contracting companies now give their long-time folks paid vacation. The "vacation" rate may not be as high as the "working" rate, but it still beats a blank.
