I'm wondering if there is anything you would recommend booking in advance during the busy tourist season (e.g. summer). I'm specifically interested in Budapest, Vienna, Prague, Cesky Krumlov, Salzburg, and Munich and surrounding areas of these places, but I welcome comments on other European destinations that might be of interest to others reading this thread.
I'm thinking of things like tours (not the long term tours, but tours of specific attractions or tours of less than a day's duration); restaurant reservations for special places that are hard to get into; concerts, shows, or spectacles--that sort of thing.
Thanks!