Last year i was in Munich for 5 days and on one of those days i did an organised tour with Pure Bavaria Tours, i chose this company after much research, as i wanted a more personal service than going with a big tour bus/group.
http://www.pure-bavaria-tours.de/pages/neuschwanstein_and_linderhof.html
The web page above details the tour we did, 99 euros per person, so it was not cheap but we were out for best part of twelve hours and it was a major highlight of an excellent holiday.
Hope this helps, by the way we travelled everywhere else in Germany by train and we found this a great way to get around and toured places like Dachau without a guide.
I would not hesitate to recommend Pure Bavaria, our guide was Mario, great person, very friendly, informative and nothing was too much trouble.
Cheers
Paul