My experience starting in the US and ending up in Ushuaia was this:

- Alaska, USA and Canada: great way to start a trip. Scenery unbelievably pretty and diverse, excellent people, easy to travel, in short a very pleasant way to 'get into the groove'.
- Central America: crossing the border from the US into Mexico is always fun (I crossed at San Diego twice, dunno about other crossings). Baja offers no gradual transition, you are throw into the deep and have to swim. Great intro to the rest of Central America. Beautiful countries, relatively easy travel, but you WILL get the occasional unexpected surprise. You´ll get used to it quickly enough and it´ll be a blast.
- South America: same as Central America all the way down to Chile I´d say. Cross the border from Peru into northern Chile and you are in another world (almost). Everything works: cable tv, warm water, pretty good infrastructure, a well deserved break after a long hard ride.

Buenos Aires is an almost obligatory stop if you want to ship back home (Santiago also an option, but it is in Chile and you are going back to Blighty I presume, so Santiago might be costly). Buenos Aires is a great place to end your journey on the PanAm: Enough civilisation for a relaxing post-trip R&R, enough lawlessness to not be boring if you stay awhile.

Moneywise it doesn´t matter North to South or vice versa, tripwise I would say it does.

Patrick, we´ve got you down for a signed copy of the 'Adventures of Shitman', but don't hold your breath, it might take awhile

Keep on truckin´

Dirk

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