Short answer: we're spending A LOT!!! There's a reason, though. Here's the story:
This past June, I went to Italy with my DD's (ages 21 and 14 at the time). It was 12 days, the trip was a graduation/birthday trip for my older DD. We had a glorious time, but DS11 felt quite miffed that he was left home--I felt he didn't possess the maturity to handle the trip, with its strange foods and different language and all that history and walking and so forth. I promised him a future trip to Italy.
Earlier this month, we came into some money. Our family values are such that education and travel are two big expenses. Looking into travel options, I found a tour Europe that includes London, Paris, and Rome. It's geared towards kids, so in London, for example, there's a Harry Potter tour. Plenty of other kid-oriented stuff, meant for family travel. OTOH, it's a very pricey trip--everything's 5-star, which generally isn't our style, but this particular tour really spoke to our family. So, bottom line, 5 of us will be flying to Europe next June. DS20 will stay home--he'll be taking a summer class. Including airfare all around, you're probably talking close to $50k for this trip. We have no intention of travelling like this every year, but I'm looking forward to the experience.
On a normal year, a travel budget of maybe $10k for the 5-6 of us is much more common. Sometimes DD22 doesn't come along--she lives in another state--and sometimes DS20 stays home (he's always invited, just not much of a traveller).