Take your vacations around your time off, like everyone else is supposed to do! There are some families in our school who take vacations during the school year, but most follow the schedule, as vacation time work is to be completed (mostly) in advance and whatever else is completed while they're gone is required to be turned in when they return.
That said, because of my husband's choice of profession, we take our family vacation at spring break and Thanksgiving break (our school is out a week at T-giving). It's busy, more expensive, but because of the career choice, those are the breaks.
Our school does allow teachers who travel over breaks to take a day or so before the break begins if they need it, especially at Thanksgiving, as we get a 1/2 day on the Friday the week before, it's almost useless to get anything accomplished on Thursday or Friday! I think there may be 2 or 3 teachers who take one or both of those days off.
As far as subs and what is expected - I was asked to sub later this month - for a middle school Math/Social Studies teacher - I'll mostly be "babysitting".
About teachers - I know many in our district who get pregnant planning on a due date between Spring break and the end of the year - their FMLA leave will cover them (usually paid) so they get that time off, don't come back until the next school year.

Talk about working the system!