In terms of the flexibility you are looking for, it sounds great. But be careful to get the right person. Au pairs are ages 18-26, so s/he will not be much older than your kids. We have three kids (2,7,12), and our au pair has had the most trouble with our 12 year-old. 12 yo doesn't want to listen to her or respect her authority as much, in large party because the child is so self-reliant, and our au pair has had trouble bonding with the 12 yo for a few different reasons. We're working on this, but the dynamic of the relationship with older kids and an au pair can be tricky, IMO. Think about what you are looking for that relationship to be and look for the right person to fill that.