I like to separate out airfare and pet sitting. This lets me look back at the vacation expense and see what could change in the future. Sometimes airfare is totally covered by points, but sometimes we pay full price. Also, we might not have pets in a few years or if there’s a house sitting exchange, then I’d like to see how that affects the total cost.
edited to add--- Airfare and pet care might seem like two weird categories, but sometimes they're more than half the cost of a vacation, so I think its very relevant. A quick breakdown of a 2 week trip for my wife and I could be something like-- Airfare $0 or $1,200, pets $600, hotel/food/sights $500 to $2,500.