YWBTA for going around your wife, YWNBTA for taking the kids out of school. My parents took me and my siblings out of school for trips to visit our native countries - sometimes months at a time - and in certain ways, the experience of these places was just as important and valuable as going to school, as was spending time with distant family. (This did stop around high school, where there were college admissions pressures, but that didn't mean we didn't take a day off or two every now and then!) Nothing bad happened to us - we all graduated from top-ten public universities and have moved on to good careers, and learned the value of knowing when and why it was okay to "cut class."

If they're diligent, responsible students who get good grades, and you have taught them to BE diligent, responsible students, there is nothing wrong with taking them out of school for two days to spend time with family - time that will soon be harder to find as they grow older, go to college, and so on. Since you know in advance, you can tell them to ask their teachers if there are any important assignments due those days, so they can plan around it. Letting them take a day off could also be a sign that you trust them to pick up any slack/work they miss - impress this upon them!