Do you budget for vacation?

I try to at have or make a rough guess at costs, which somewhat qualifies for a budget. It's usually nothing as formal as a spreadsheet...more along the lines of x miles at $.35 per mile for gas, y nights at $xxx per night for campground, some for admissions or food, and so forth. Basically, it's a back of the envelope sort of computation, perhaps even involving the back of an actual envelope.