Chantilly

Allow 30 minutes to walk following signs from the station, and note that it's not as well signed on the way back. Taxi should cost about €10 one-way.

Rick Steves' Paris says that the free city bus (called DUC) "runs infrequently from the train station to the château, and usually is not well-timed with train arrivals." See schedules at www.oise-mobilite.fr/. For this Friday, I saw departures from the station at 9:16, 10:20, 12:30, and 13:44. None in between those but I did not check for later. Does not run on Sundays.

It's quite different from Versailles, less grand and the gardens not nearly so manicured.
We liked the gardens and stables at Chantilly more than the Chateau itself (refer to RS Paris about that). The gardens include a lovely little grotto and the stables clearly show the attention that was lavished on the horses there by Louis-Henri de Bourbon (he who thought he would be reincarnated as a horse).
We were there on a rainy day and it seemed as though we were the only ones there - a far cry from Versailles. We drove, so I have no first-hand experience with public transportation, but Laura covers what RS says about it.

We walked both ways between the Chateau and the station, and I wish we hadn't because there is a lot to see: stables, absolute gem of an art museum and the gardens.

I can echo the comment about minimal signage. Many years ago I took the train there from Paris, alone, on a Sunday, and I never made it to the main chateau that houses the Musee Conde. There was some kind of abandoned castle-like building that lured me and I ended up spending my entire time walking around it, trying to find the entrance to the museum. To this day I can't figure out where I was!

I'm really torn now- I am purchasing the Paris Museum Pass so I can go either way- I have not been to Versailles either, and now am wondering if I should go there instead. Second guessing my decision!

Versailles is a waste, IMO, unless you spend most of your time out in the gardens and outlying structures like Petit Hameau and/or book a "visite guidee" (tour to areas not otherwise open to the public). The main areas inside the palace are so packed you can't really see anything except the pushing & shoving people surrounding you.

I know you are traveling now but would love it if you come back to this thread and update how you worked things out. Planning Chantilly on my next trip!

I went to Chantilly as a train day-trip from Paris on July 16, 2017. I walked to and from the domaine on a very hot day. It's 30 minutes (walk straight out of the train station; you'll see intermittent signs; follow the crowd!). I actually enjoyed Chantilly more than Vaux-le-Vicomte (but it's been since 2001 since I've been to Versailles, so I can't really offer a comparison to that). The art was amazing, and there was more of the building to see than I expected. The gardens were pleasant to walk in. I had lunch at the Hameau restaurant in the gardens. I did not plan well, so I arrived too late and didn't stay long enough to either see the morning or afternoon dressage show at the included horse museum. Hope you have a great time!