Here is a practical tip for those who want to skip the lines, and are not the morning bird type, like myself. Completely serendipitously I discovered that if you book a guided tour from Versailles itself (no third parties) to the king's private apartments, you'll skip all the lines, no matter what day or no matter the size of the line. My wife and I visited on easter weekend (worst timing possible) and were extremely discouraged by the HUGE lines: the entire front square was packed (est. waiting time 2h). We had booked the 'passport' ticket that gives you all access, and for €10 extra the guided tour in the apartments (which you otherwise can't visit). The apartments itself were worth the money, but the best part was for sure when our guide (we had the 12pm slot) walked us past busloads of astonished (and sun-scorched) tourists straight to the front of the line and into the castle. All in all we waited 5 minutes in the airconditioned waiting room for the guided tours (Building on the right side of the entry gates) and never waited a second in line. So to all my dear fellow WHS enthusiasts who happened to plan a Versailles visit (and don't like 8:30am on a holiday) ... you know what to do.