Renting a car in Munich vs taking a tour by coach

I’d take the extra day car rental and drive to Fussen and spend the night, then visit Neuschwanstein in the morning before starting on the RR. You need to make a reservation to visit the castle, so better to tour it first thing in the morning rather than be rushed trying to make an afternoon tour after visiting
Linderhof and other places on the way.

There is a really nice Hotel right at the base of the mountain below the Castle. Right where the horse drawn carriage departs from. It has parking on site. And you can get rooms with balconies that have a view of the castle. If you contact the hotel they will get you tickets for the castle so you don’t have to spend time picking them up.

It is really a spectacular view as the sun goes down. Sitting in the balcony eating desert from room service.

I agree, drive and stay near the castle. We stayed in Fussen and drove around to Oberammergau and had lunch in Garmish.

"Arriving by train from Paris, we will be staying three nights before heading off to Frankfurt, then to Lisse... We are planning on doing at least a one day trip while in Munich to the Neuschwanstein castle."

With only 3 nights in Munich after the train ride from Paris, you only have 2 full days for the area, so spending a whole day on Neuschwanstein (built in the 1890's, not a real castle) and Linderhof, etc. would mean only ONE full day for Munich.

So the question is, why bother going to Munich at all? If you're sold on the mountains, then you might just skip Munich and head to the Füssen area for your 3 nights instead. Either that, or just stay in Munich so that you have a chance really see the place.

It's a fairly long car trip between Munich and Frankfurt on the Romantic Road. Then another long car trip to Lisse.

So instead of the detour to Füssen, I would consider breaking up the long Frankfurt > Lisse journey you have in mind with a stopover in the Middle Rhine Valley, which is on the way to Lisse from Frankfurt and home to dozens of genuine medieval castles and castle ruins.

Middle Rhine Valley = yellow section on this map.

Map of castles between Koblenz and Bingen: http://www.loreley-info.com/eng/rhein-rhine/castles.php

Rheinfels Castle (tours): https://www.youtube.com/watch?x-yt-cl=85114404&x-yt-ts=1422579428&v=qxFF80wORNQ#t=32

Rheinstein Castle: https://www.rheinwanderer.de/wp-content/uploads/2018/01/3WmK_09_Blick-auf-Burg-Rheinstein_1000x667.jpg

Marksburg Castle: https://upload.wikimedia.org/wikipedia/commons/e/e3/Maeuseturm_Burg_Ehrenfels_Bingen_Rhein.jpg (English tours possible) https://www.marksburg.de/en/

Pfalzgrafenstein toll station: https://www.tripadvisor.com/Attraction_Review-g1183932-d2189406-Reviews-Burg_Pfalzgrafenstein-Kaub_Rhineland_Palatinate.html

Castles near Bingen: https://upload.wikimedia.org/wikipedia/commons/e/e3/Maeuseturm_Burg_Ehrenfels_Bingen_Rhein.jpg

Russ is exactly correct. Why bother traveling to a destination if most of your activity there will be daytrips to other locations.

PS - the Romantic Road is anything BUT romantic.

Thanks all you have made some great suggestions, and very valid points..
First, the ONLY time we will be planning to drive is from Munich to Frankfurt. The reason being is I want to actually visit neighboring Hanau, where I was stationed in the Army during the mid 70's. Just want to see how it has changed, the kaserne, and the apartment I lived in. (Looked it up, the apt still stands, kaserne is now a school, and housing.) Just leisurely tour around, not dependent on public transportation, before taking the ICE train the following morning to Amsterdam (Schiphol) and bus to Lisse, for 3 nights for the Bulbflower Parade. Hotel in Lisse is already reserved. Set in stone. Had to for the parade weekend.

Original plan was figuring we'd be getting into Munich the first day at the latest, around 3:30pm, would give us an afternoon/evening, and the next day/night in Munich, day trip on the 3rd day to Neuschwanstein, (maybe rent car for that) but then, for sure, check out, rent car, drive to Frankfurt, etc.etc....
The idea of staying practically at the foot of the castle or in Fussen, just never occurred to me, that is a great idea. I wish I had more time to visit all those other wonderful places in the Middle Rhine Valley. I feel bad Russ, you took all that time with those suggestions, I am sure this won't be our last trip though.

From what I see, unless I'm reading it wrong, it's around 4 hours straight through from Munich to Frankfurt via the RR. not including traffic of course, I don't care really about seeing Frankfurt other than getting there before dark so I can tool through Hanau, see my old stomping grounds. Start out early, probably will stop at Rothenburg, and hopefully see some glorious views along the way.

It's been 43 years since I was last in Germany, a lot has changed I know, but the beauty and grandeur of Europe are still the same. I want to show my wife some of my favorite places I visited while I was stationed there. Munich was definitely one of them, as was Garmisch-Partenkirchen.(thank you Barbara) heck, the first time I ever skied in my life was on the Zugspitze. Saw the re-enactment "Burning of the Heidelberg", visited Berlin before the wall came down. Was the tour coordinator for my company so got to see a lot. This will be my wife's first trip just about anywhere except the east coast of the USA. Now that we are retired, I want to give her the travel bug. A glorified "hop on hop off" of some the best sights so we can then plan on spending more time in specific places in the future. Again, thank you all for your input!

"...you took all that time with those suggestions, I am sure this won't be our last trip though."

Those places will wait for you. They were there when you and I were there in the 70's, and they were there 800+ years before. Like you, I had stuff to do there, and I didn't get to see it all.

"I want to give her the travel bug."

If she doesn't have it, your future trips to Germany may depend on how successfully you infect her. My first "nostalgia trip" was fun - mostly for me that is, much less so for my "her." I suggest being thoughtful about the inherent differences in your two perspectives; no doubt about it, my personal enthusiasm for revisiting "stomping grounds" was far less infectious than I'd hoped. Better results than mine may depend more on the "incidental" or "secondary" things you choose to include.

So "do as I say, not as I did"... What sort of stuff made her willing to return to Europe for this 25th celebration? Lisse sounds like a good bet. On your way south from Frankfurt - or on the way back - you might think about some stopover time in one or more of the Main River Valley towns. Here are two suggestions for places to pull over for a break, places you might find a romantic setting, a nice meal, some easy strolling/sightseeing, etc.

Miltenberg (south of Aschaffenburg)
Sommerhausen (south of Würzburg)

When you come back for your 30th, think about some time on the Middle Rhine, maybe book a place or two like this one.