visiting Fussen area in June...... any suggestions?

My favorite part of Germany---it's so hard to choose, there are so many pretty villages. Garmisch-Partenkirchen is nice and you could visit the Zugspitze as well. Going to make a bold assumption that you already plan to visit Hohenschwangau to see Neuschwanstein (my husband proposed to me there!). It's small, but with the 2 castles, it packs a nice punch.

Salzburg would be a bit of a drive, but worth your while---but if you only have 2 days/nights, it would definitely take an entire day, lots to see there & simply the countryside.

You will not be far from Schloss Linderhof, which was Ludwig's favorite castle. It is a gorgeous small one bedroom rococo castle in the mountains that gave him the solitude that he really wanted. My German cousins readily point out that Neuschwanstein is only theater and indeed was desi8gned by the theater set designer and has no real historical significance.

I loved Fussen-their little museum was interesting.

On your way from Salzburg to Füssen you have to leave the Autobahn/freeway anyway. Therefore I would suggest to stop in Bad Tölz. A cute little town and worth wile to do a short walk in the old part of the city: https://www.germansights.com/bad-toelz/

From Bad Tölz I would take the Deutsche Alpenstraße/German Alpine Road to Füssen: https://www.germansights.com/aroad/
In my opinion the extra hours are well spent.

Füssen is nice as well and I would visit Hohenschwangau and Linderhof Castle, take a walk in Füssen, ride a boat on lake Forgensee or just relax at lake Hopfensee. From almost every place in this area you can enjoy the scenic mountain view.

Neuschwanstein I would rather admire from the outside. Hike up to Marienbrücke - the best way to do would be through the Pöllat gorge: https://www.hohenschwangau.de/en/nature-surroundings/hohenschwangau
But no idea if it will be open next year - needs to be checked shortly before.

thank you to everyone for your helpful replies.........