Escorted vs Self guided tours

Thinking about a trip to Europe, Australia or New Zealand?  These are prime destinations to take advantage of a prearranged tour package.  Most of us think of tour packages and we think of bus trips with a group of other travelers.  But most tour companies also offer prearranged self guided tours.  No buses, no groups, and you get to travel at your pace.  You take advantage of the tour company's contacts and buying power while still being able to travel independently.