Do we need to hire a guide for the palace and grounds or are guide books and/or audio guides available at the entrance We will be arriving from Paris by train
No need, in my opinion, to hire a guide. We spent most of a day there with just a guide book and took our time touring the palace and grounds. Don't think having a guide would have enhanced our trip at all -- and probably would have felt rushed.
We also went on our own. We used their audio guide.
No need at all for a guide. The palace is well signed in each room. The gardens should be visited on a fountain day. Just read a bit about the Trianon, Palace and Hameau and enjoy the day. Here is our visit for the fountains only. As you can see the garden is not interesting when the water isn't running.
https://janettravels.wordpress.com/2016/02/15/fountains-of-versailles-a-little-chaos/
No guide needed. Enjoyed the grounds more than the palace, but that's just me and palaces.