Austria Itinerary help - 2 weeks

For the route Zell am See to Neuschwanstein to Innsbruck the pure driving time (without any stops, traffic jams, etc.) is about 6:30 hours. The first leg is about 260 km, the second about 100 km.

It is doable, but you must start early. I don't know how long you will have to wait to get in the Neuschwanstein Castle.

When you say "Salzkammergut" what do you mean, as it is a vast area. Hallstatt? The lakes? Regardless, I think 3 days is a lot. And one day in Innsbruck is too few. You may want to consider a base camp where you can enjoy the Salzkammergut region and Salzburg and not move to new accommodations. The drive from Zell-Füssen-Innsbruck is doable in a day. Check to see where you can drop the car as well. You may need to do so at the airport and if on a Sunday, check to see if the location to drop the car is open as well. And by the time you drop the car and catch a train and get settled in Munich you will find that Day 15 in Munich is more like just and afternoon in Munich.

Also, you say "Day 1" is in Vienna. Is that the day you arrive in Vienna or the first full day? Because you are giving yourself 3 days (at most in Vienna) and a full week in the greater Salzburg area. Vienna is one of the great cities of Europe and I think you are giving it short shrift.

If you skip Schloss Neuschwanstein, from Zell am See you can take the Großglockner Hochalpenstraße (should be open mid May) to Lienz. From Lienz (sunniest city in Austria) you can drive through Südtirol with a stop in Bruneck, Italy (with good weather visit the top of Kronplatz too) then Sterzing, Italy, then over the Brenner Pass to Innsbruck. You could also swing further south in the Südtirol Dolomites time allowing (Grödener Tal, Seiser Alm etc). Should be a lot of wildflowers blooming.

Anybody smart enough to plan a stop in Steyr won't get much useful advice from this forum, but as a 4 time visitor to Steyr, & the Royal Castles, I suggest this. Forget third rate Munich. Shift the Munich days to Innsbruck to visit the spectaculary scenic Oetztal, Kraunnertal, and the valley in between the two tals. Its a slow drive from Innsbruck to Fussen, so take train. Local transport will get you Neuschnstein.

BTW: If you must waste time in Munich. Here's how to properly pronounce it in German: Munken.

Id suggest this itinerary:

1) Fly into Vienna
2) Day 1,2,3 - Vienna City
3) Day 4 - Drive to Melk/Wachau Valley/durnstein & stop overnight in Steyr
4) Day 5,6,7 - Salzkammergut area (Visit Salzburg from either here or Berchtesgaden)
Omit the stay IN Salzburg (visit Salzburg from Berchtesgaden base. easy, 30 minute drive.)
6) Day 8,9, - Berchtesgaden
7) Day 10, 11 - Base in Zell Am See and visit nearby sights (Kaprun, Grosslockner, Krimml)
8) Day 12, 13, 14 - Drive from Zell Am see to Fuessen. Neuschwanstein Castle next morning (13). Tegelberg luge, Tegelberg cable car, Zugspitze trip (nearby Ehrwald), Wieskirche, etc all from Fuessen.
9) Day 15 Omit overnight stay - drive from Fuessen to Innsbruck.
10) Day 15, 16 - Drop car at Innsbruck and train-ride to Munich.Spend 2 days in Munich
11) Day 17 - Fly back from Munich

One bit of insight.

Weather in the Alps is variable and erratic most times of the year, but spring is a particularly wet and volatile time. Without the benefit of a short-term forecast, you simply can't plan on any given day in the Alps having cooperative weather. So rather than having, let's say, one single day written in stone to visit Berchtesgaden, keep your schedule a little more flexible in case you get rained (or fogged) out. You will have a car, and several of the locations you mentioned are easily accessible from each other, so you can make decision about where to visit on a given day on the fly. Salzburg, for example, is far less weather dependent than Berchtesgaden and the Grossglockner.

Also, consider staying your last night at the fantastic Therme Erding resort near the Munich airport. It will give you a nice chance to relax and decompress before your flight.

May 21 is a public holiday in Austria. As it falls on a Thursday, many will take off the Friday, so expect things to be busier than usual. Also shops will be closed.