Traveling from Munich to Innsbruck with a party of eight adults, wanting to take in the Neuschwanstein Castle along our route.
What is our best transport option? Considering ease of travel, costs, flexibility, etc, would it be better to rent a one way van and drive at our own pace; or depart and return on a castle tour and then train to Innsbruck? The trip is in late March 2024.
We took the train from Munich using the inexpensive Bayern tickets. Hopefully, someone else will answer your transportation question. I just want to suggest that if you are going to Neuschwanstein, you really ought to see Hohenschwangau as well. It is basically across the street. Very little of Neuschwanstein is furnished and the king never really lived there. Hohenschwangau was the family home. It is completely furnished and you will get a lot of information on the family and King Ludwig. The Hohenschwangau tour provides good context for Neuschwanstein.
You're likely to see a LOT of Euros flying out of your wallet to rent a van in Munich for a day and then drop in a country other than Germany. Feel free to contact whatever rental agencies you wish if this sounds best to you.
If I had to make this journey myself with 7 others, I don't think I'd choose to drive anyway. It's March, with March weather to deal with. Since you are considering a round-trip commercial tour from Munich and the expenditure of an entire day on this outing, you should also cosnider a round-trip independent tour... The train to Füssen is direct and takes 2 hours (9:41 - 11:56 for example.) There's a direct train returning to Munich 5+ hours later at 17:05 (ar. 19:19.) (Other journeys throughout the day require a change of train along the way but require roughly the same amount of time.) Also, there's a day pass to cover these train trips called the Bayern Ticket. Read about it at the page below. It will also cover the shuttle bus between the station in Füssen and the final N'stein bus stop. You should buy two of these to cover your large group. Should cost less than €120 altogether for the trannsportation. Just get them at the station or using the DB app on the day of travel:
https://www.discover-bavaria.com/tickets
Video on this trip:
https://www.dailymotion.com/video/x7661ny
It's not clear how many days you have in Munich, but this way you can be flexible about which day you choose and use the weather as a guide.
Munich > Innsbruck trains:
I have no experience renting vehicles in Europe, but others have mentioned that it's very difficult to find a vehicle large enough to accommodate a group the size of yours when there is also luggage to transport. Just another reason to choose the train.