Most parents have to book their summer holidays well in advance at work so by May/June you can usually get those dates from parents. I then used to match it all up and take my holidays to coincide with the weeks most were off anyways as a way to minimize disruption and income loss. The last week of July and the first week of August are the most popular for my gang because of there being the holiday in the middle so they get to add an extra day to the time. I always liked having the last week of August off to get things organized for my own kids for back to school - the shopping done, everything labelled, baking down in the freezer and the chance to do some fun things before the return to school.