We did the Versailles tour with Blue Bike Tours. It was great, especially after a few days walking around Paris. The guide was excellent and my daughter quickly bonded with the other kids on the tour. One thing to note: if you arrive at Gare d'Austerlitz on the metro you need to go upstairs to find the meeting point. We screwed this up and ended up meeting every one else in Versailles (sorry JB!). But this is highly recommended as the best way to see Versailles. The grounds are the best part and you won't see them all on foot.