Will be spending 1 day in Versailles in September (first time). Any suggestions as to: 1) just using audiophones included in the price of Le Passeport ticket; 2) per Rick Steves' book, signing up for the 1.5 hour English guided tour (booked through the palace's website); or 3) paying a lot of money for a small group private tour company such as Viator?
We always just get the audio guide when we arrive into the palace.
Biggest issue with Versailles is walking between the main Palace and the outlying palaces through the garden. It might be worth it to have some transportation there, but I don't think a tour is really necessary.
Audio guide or group tours are plenty. Find some books or videos before you go to familiarize yourself with the history and layout, that will go a long way towards enriching the experience. It will also help you prioritize and plan your time. I agree that getting around the grounds can really add stress to a long day so look for the tram that runs between the three main buildings. It was a life-saver for us!
If you have mobility issues and think that you might not want to tackle the RER C - especially hot and crowded in the summer months - then you might consider a half-day group tour. You'll be taken from the pickup spot by air-conditioned bus, and dropped off in the same spot.
If you're able to get around and can follow basic signs in the train station, getting to Versailles is easy to do. You can search Google for exact instructions on how to purchase train tickets, etc. The official Versailles website gives very good directions, layouts of the grounds, etc.
If you're interested in seeing other parts of Versailles that the masses don't get to appreciate, you might enjoy the English-speaking tour. The benefit is that you start the "behind the scenes" part of the tour while everyone else is trying to squeeze themselves inside the Hall of Mirrors - when your tour is over, you can go back inside the chateau after most of the crowds have gone. I'd advise getting to Versailles a little early, so you can get in the right line and be on time.
You can rent either bicycles or golf carts to get around the grounds, which are truly enormous. If you get to the town of Versailles early enough, you can buy a picnic lunch to take with you and enjoy on the grounds - or bring something from Paris.
Sorry - I forgot to mention that you should go on the earliest English-speaking tour available, to get the maximum benefit and the least number of crowds.
Also, the tour booked on the official Versailles website is a small group tour.
If you go on a bus tour with Viator, there will be a much larger group with you.