I grew up travelling and it made a literal world of difference for my education. It also made it difficult for me when we moved back to the States and I was put in a regular public school b/c I could talk about Paris and Berlin and London in a completely different context. When you've actually walked in the trenches...it's a whole different story. I want my children to experience the same things and I agree w/ Princess Michelle's take on the schools trying to control the family too much. My oldest graduated from PS and my now 19yo was in PS off and on until 9th grade when I pulled her out b/c of a teacher on a power trip. While PS is a good fit for many families, some DO send their kids just b/c it's the societal norm and they appreciate the social engineering aspect, not b/c they've researched their options. You don't know how many times I get "the look" followed by an "I would NEVER even CONSIDER such a thing!" well, why not?
As far as unschooling goes, we are adapting that more this year. I have a curriculum for DDs, but it doesn't take long at all to get through the lessons. Unschooling is generally "child led learning" which means that we learn what they are interested in. 11yo had it in her head to fill in a map with the 2 letter abbreviations of all the states, color the Mississippi, and then color all the states they have been to.
They are currently on a mission to plan a trip to ND, SD, MT, & WY so that I can say I've visited all 50 states (those are the only 4 I have left), so they are researching sights we might see and trying to figure out a way to convince DH that we'll be close enough to
Disneyland!

They are using math to figure out how far the trip is and by averaging 60mph how long it will take. Geography, of course, plus social studies learning about the history and attractions we might see. They are also using science to watch weather patterns both here and there to determine when might be the best time to go (DH is a masonry contractor, winters are usually slow for him)
8yo saw a whale show on TV and decided she wanted to know more. In doing these kinds of activities, we learn about migration patterns (geography), the animals themselves (biology), usually there is some art involved, DD listened to whale song, then went to the piano to try to duplicate it.
When they are interested in the subject, they learn SO much more about it than when it's forced upon them. As I said, we do use a curriculum still b/c I think it's important for them to realize that when they have a job, they aren't going to have the same kinds of freedoms they have now, but I also want them to see that learning is a lifelong joy and it happens all on its own, without a person telling you you have to do it or HOW to do it.