So with some places like South East Asia, generally accommodation is really simple - you basically just need to rock up and there's enough people trying to drag you to their hotel.
With Europe and Japan, it was less simple, and you probably want to have some accommodation plans, especially if you want to get the best prices.
Just wondering, for South America (Argentina, Brazil, Peru, Bolivia and Chile), is it necessary to book everything in advance? We're going for 7 1/2 weeks and we kind of have a rough plan of where to go, but we're prefer to be as flexible as possible if we could.
Also might mention that we're happy to stay in hostels (and dorm beds) if nothing else is available but would probably be interested in staying in cheap hotels and the occasional expensive hotel.