I think you did the right decision. I feel the same about Munich like RichardInSF and normally stay at the Charles. In Salzburg I stayed recently at Sacher which was nothing special. While the location of Mönchstein is a little remote I don´t think you would have had a better stay at the Sacher, more the opposite. Personally I never stayed at Schloss Elmau but a colleague did. He reported similar problems. Service not good things like concerts you pay but probably don´t use. He had as other here the opinion if you stay you must choose the retreat to have a decent experience.