One Day: Munich to Neuschwanstein to Augsburg

It sounds like a busy schedule to me.
Keep in mind, tickets to Neuschwanstein must be picked up at least 90 minutes before the start time of your guided tour.

tickets to Neuschwanstein must be picked up at least 90 minutes before the start time

That was one of my concerns. That only leaves you with 60 minutes to take a 40 minute tour (assuming they give you a tour time exactly 90 minutes after your expected arrival time), and return to the parking lot in Hohenschwangau. Actually, you had better make it at least 100 minutes after your anticipated arrival time, since it will take time to find a parking spot, walk to the ticket kiosk, and possible wait a few minutes in line (although when I picked up tickets, there was no line).

But the bigger problem, as I see it, is that you have 4½ hours of sightseeing and over 2 hours of car travel before you need to arrive at precisely the correct time to pick up your tickets for Neuschwanstein. What could possibly go wrong with that?

It might be better to start with Neuschwanstein, so you could better predict your time of arrival, then to Ehrenburg, Linderhof, and Ettal in that order. I would rate Ettal as the least interesting of your destinations, and it could be omitted if you run late. Even then, you had better leave some leeway for arrival at the Hohenschwangau kiosk to account for a delay in getting the rental car or traffic delays on the way.

Assuming you are planning to eat breakfast before you pick up the car, your schedule has no time to stop for lunch. Are you really going to go almost 12 hours without eating. Well you have 90 minutes between the time you pick up your tickets and the tour time, and it only takes about 45 minutes to get up to the castle, so you would have time to grab a brat on a roll at the Schlossrestaurant just below the castle, but by then it will be after 3 PM.

The walk from the parking lot to the ticket kiosk at Linderhof is short as is the tour of the palace itself, but the grounds should not be missed. When I was there in 2007, I spent about 5 - 6 hours exploring the whole place (and lunch). I had planned to go to Ettal on my way back to Oberammergau, but I spent longer at Linderhof than I had planned, and it was my first full day in Germany, and I was badly jetlagged, so I went directly back to Oberammergau. I had previously researched Ettal and didn't really find much of interest, so I chose getting back to my room over Ettal.

Thanks for the reminder about picking up tickets 90 minutes in advance; I had seen that but forgotten it. I believe we will reverse the route to head straight to Neuschwanstein first, so we're not stressed about the possibility of getting there late as we tour the other spots. And we'll delete the monastery.
-It looks like Linderhof Palace is open until 6:00 pm. Do you know if the grounds are open later? Are the grounds the same as Linderhof Gardens?
-We were thinking of a picnic lunch at Ehrenberg ruins (but maybe we'll change that to the lake near Hohenshwangau) and dinner after visiting the last site. If anyone has a restaurant recommendation for somewhere between Linderhof and Augsburg, that would be appreciated!
-Does anyone know about needing a driving pass for Austria, if we're only going as far as Ehrenberg? I've read mixed answers.
Thanks!

We drove past the Ehrenberg Castle a few years ago and as I recall the roads are just two lane roads not the Autobahn. If I remember correctly the pass is only required for driving on the freeway, but I may be wrong. I'll let others provide additional information.
I think this plan could be doable, but very rushed. Also remember that the driving estimates from Google maps can be way off. Once time we drove to a destination and based our timing on Google maps and it took twice as long as indicated.

Have a great trip!

Schedule is too tight - neuschwanstein is going to be crowded in June, long lines just to get your ticket (with reservation) and before you can enter the castles. The lake next to the castle is very nice, you can swim in it. Take your time to enjoy it, don't rush and stress yourself.

I also plan to visit Neuschwanstein Castle in June of this year. We will arrive by the Bayern train. Can you suggest how much time I should allow for the line at the ticket office? I haven't purchased any of my tickets yet, as I am stewing over that 90 minute requirement. Thanks. (And I hope it's ok to jump in Angela).

We were at Neuschwanstein last June. I think we arrived at ticket office to pick up our reserved tickets about 2 hrs to 2.5 hrs before our tours. It was around 10. 25 am, the ticket office was very crowded. There was long line on reserved ticket line. There was also line for the shuttle bus to Neueschwanstein. I was glad we had plenty of time to allow the waiting in line and we could see Mariene bridge before tour.
We stayed in Fussen, so it was a very easy trip.

FYI--you don't always get the time you requested at the castles. We were there last April and it took me 3 tries to get anything close to what would work for us since we were day tripping from Munich and bound by the train schedule. The reserved ticket line was a 20-30 minute wait. The person working was really nice and switched our itinerary on the spot (we did both castles plus the museum) to be even more workable and give us time for a quick lunch. There was a line for the bus to the bridge (15 minutes or so) as well.

Thanks so much. Your replies are very helpful.

There is no margin for traffic, or searching for parking, possible walking to the attraction from parking, and waiting in lines. All those things eat up time too.