A must see. Step back into history to see how the aristocracy lived. This ia a nice tour, with an audio player that tells you about each room. The audio describes what is in each room, how it was used and gives you a history of what occurred there.
Don't forget to look up as many rooms have gilded or painted ceilings. My wife and I enjoyed the Hall of Mirrors and promenaded down the middle of it, hand-in-hand. The furniture and walls of Versailles were very ornate. I am not into antiques, but the furniture here was quite impressive.
The gardens must be quite a sight in the spring and summer. Unfortunately, we were there in the late afternoon on a cold November day. The gardens are big enough that we quickly lost site of the house due to the fog. There was a horse and carriage for those who want a guided drive through the gardens. It was too late and too cold for us, but would make a nice romantic ride at another time.
We had rented a car and stopped off at Versailles on our way back from Normandy. If you plan to drive back to Paris, be advised that there are few road signs that say Paris. In fact, we saw none. Get a better roadmap than we had (all of France). It was rush hour when we left, and we got bogged down in traffic, not knowing which way to go. Luckily, I had my handheld GPS so I could at least tell when we were going the wrong way (most of the time). We hit several small towns before we found the A13 again. It took about 90 minutes to cover the 12 1/2 miles to Paris.
I recommend you get to Versailles early and either take the train for Paris or leave early enough to beat rush hour traffic.