How many hours are enough to visit Neuschwanstein and Hohenschwangau castles in Fussen in one day?

Is there anything else to visit in Fussen?

Well we really prefer Schloss Linderhof to either of these palaces. (These are palaces not castles - they were not built as fortifications and are several hundred years too new to be castles.)

Lots of good info here on these castles (as they are referred to on their own webpage):

https://www.hohenschwangau.de/543.html

There are also some smaller sites to visit in Fuessen that I thought worthwhile. It is a cute, little town. And the color of the river was a beautiful torqouise when I was there! I spent 2 nights in Fuessen. I was quite surprised to see a Woolworths... if you know that old store.

Also nearby, is the beautiful Weiskirche on the way to the charming town of Oberramagau.

Sorry... typo, turquoise.

There's enough time that you can go to your hotel first and LEAVE THAT LUGGAGE you are worried about and THEN go see these various sights.

Fussen is a pretty town for a stroll, walks along the lake and river, cablecar up Tegelberg, great hiking trails from there (we did the Reitweg hike which ends at the rear of the Neuschwanstein castle near the bridge, so much nicer than going up from town with the crowds).

Depends how long the line is with Neuschwanstein.
Linderhof has very nice grounds and I think you can see them without a ticket. If memory serves me right they didn't take the ticket till we entered the house. I only remember the piano and kitchen table. I always love seeing the kitchen and it was not on the tour. I would stop and walk through Oberammergau on your way if you are coming from Ettal and Munich.

I found the tour through Neuschwanstein very a lacking. We walked past many rooms without any explanation from the guide . There are so many people visiting that I guess they just move you along. The area both castles are in is beautiful, though.