If you're planning on doing a few castles in Bavaria, we found the Bavarian Castles pass very useful.
It's vaid for Neuschwanstein(but not Hohenshwangau), Linderhof, Herrenchiemsee amongst others & is valid for 2 weeks from when you first buy it/use it.
If you go onto the Bavarian castles website it will show you where all the palaces & castles are in the region.
You just buy it from the 1st Palace/Castle you visit.
It cost us €35 for the 2 of us last October, saved a lot of fussing about for change & it paid for itself after seeing 2 castles.