Vaux-le-Vicomte

The nearest train station is Melun, accessed by trains on the R line from Gare de Lyon, or by the slower, but more frequent RER D.
You then need a cab/Uber or similar from there, because the shuttle is not running due to Covid. It is maybe a 15€ cab/Uber fare each way; cabs might need prebooking but Uber is definitely available both ways.

I've visited there with my own car. Enjoyed it very much...

The nearest station is Melun; for the last few miles you can take a taxi.

The train is the Transilien/RER line "D" from gare de Lyon. Takes around an hour plus taxi.

Or as said above, the "R" which is nonstop but less frequent.

Thank you so much, both of you! I don’t usually do day trips from Paris when I am there, so excuse my ignorance. Would I purchase these train tickets in advance, on line? I won’t have a printer, so will there be an electronic version if I do that? I could also go to the Gare de Lyon the day before and get paper tickets otherwise. It is worth it, right? Have been to Versailles and Fontainebleau, and other chateaux in the Loire Valley. But I’ve heard that this place is pretty unique and spectacular.

If you have been to Versailles and Fontainebleau already, then this is worth it!

The tickets are bought on the regular metro ticket machines. You can buy a ticket to Melun from anywhere in Paris and it will include the metro fare (hold on your ticket to the very end!) and be valid both on the R line and the D line. Also, you can buy two tickets in Paris to cover your round trip and avoid using the ticket machines twice: a Paris-Melun ticket can also be used for Melun-Paris.

But given that a round trip is about 16€, it could make a lot of sense for you to get a "Navigo Decouverte", which is a weekly (valid Mon-Sun) pass costing 23€ (+5€ for the card if you don't have one from a previous trip) and valid on every single train and bus in the entire Paris region (Ile de France), which stretches all the way to Vaux le Vicomte and beyond.

When we went there a few years ago, we traveled from Paris and got at cab at the station. We didn’t have phones, and the folks in the chateau gift shop called a cab for us when we returned. It was easy. It was a very nice day and a highlight of the trip for friends who had never visited France. Safe travels.

We did this several years ago and did what Denny did -- got a cab from Melun and the gift shop called us a cab to get back to the train station. This was my favorite chateau visit.
https://janettravels.wordpress.com/2010/09/20/vaux-le-vicomte-our-last-chateau/
Note if you have an ND for travel in Paris, that will take you to Melun. Otherwise just get a ticket to that station on the machine at the train station before travel -- you can get it the day before to make the next morning easier if you like -- tickets are good 'forever' (or until they stop using paper tickets which is supposed to be next year.). Be sure you validate your return ticket before boarding the train. If there is a turnstyle to the platform that will validate the ticket; if not then there will be a machine to 'compost' the ticket. It is important to do this to not be fined for not having the ticket. If not validated it is the same as no ticket. (and if you have an ND and there is no turnstyle to the platform there will be post somewhere with the little swirly patch that you use to validate that ride on the ND)

Vaux-le-Vicomte is very worth it.
It is absolutely wonderful. Much less crowded than Versailles or Fontainebleau, and it’s a delight. It also has a very good café. The movie Man in the Iron Mask with Leonardo di Caprio was filmed there, a very good movie worth seeing before you go.

Thanks for the reminder about the café, Susan.

I remember having an excellent meal there with my wife several years ago. Good memories...

Nigel, it was a surprise to us how good it was. Hopefully it still is. The outside tables in a lovely setting is a bonus.

I have a happy memory of sharing a pastry with your wife at Carette… : )

My Facebook is showing me reminders of a trip to Vaux-le-Vicomte with a beloved former boss and her husband at this time six years ago. Sigh. We went on a candlelit tour afternoon/evening; it was lovely.

remember it well, Susan

Thanks for the help, everyone! We are currently in Burgundy with a car, and decided to make the drive to Vaux-le-Vicomte yesterday instead of taking the train from Paris in a couple of weeks. For us, it was a matter of simplicity and Covid safety. I wanted to report back to everyone that it was a wonderful visit. Very few people there (our tickets were for 11:30 am on a Wednesday), terrific audioguide. The audioguide is included in the price of the ticket, so I highly recommend it. Got our 10,000 steps in wandering the grounds afterwards. You do need to get your tickets ordered online to play it safe. We saw one couple who arrived without tickets and they had to wait an extra 30 minutes to go in: in spite of the fact that there were none of the crowds that a person would typically (in pre-Covid times) experience in a place like this. Also, they tell you that you don't have to wear a mask inside the chateau if you've been vaccinated and are over 18 (of course, you need to show your passe sanitaire to get in), but nearly everyone wore a mask all the same. People are much more cautious about Covid here than back in the USA - at least that has been our experience over the past six weeks.