South America is divided into 2 zones for most mileage programmes, and 3 for others. As far as I remember without going on the sites and looking, for Mexicana and AA Colombia, Peru, Venezuela, Brazil = Zone 1, Argentina, Chile = Zone 2. You usually only need 30k with AA for North America - Colombia, but an extra 15k or so to get to Argentina.
For LAN, it's MESSED UP. LAN is a terrible programme for Argentina - North America. If you're thinking about joining an airmiles programme go for AA. LAN and AA are partners, so anytime you fly LAN you can put your miles onto your AA card. But LAN throws Argentina into a different zone than the other programmes, because all int'l flights on LAN to/from BA go via Santiago or Lima. So they want more miles than any of the other airlines for a North America - BA flight. On top of that, the routes are messed up, every LAN flight goes through Santiago so you can tack another 4 hrs or more onto any trip to North America.
Air Canada, don't even talk about it, it's crap, and they share routes with LAN. So I've got a horrible miles flight that with their messed up programme I managed to get for 50k. A flight to Vancouver on Mexicana = 17 hrs, on AA = 20 hrs, on Air Canada = 27 fricking hours. BA - Santiago - Toronto - Ottawa - Vancouver. If I wanted the more direct option, which was BA - Toronto - Calgary - Vancouver it was 100k. If I wanted the better route BA - Toronto - Vancouver it was 150k. On my way home I have a 40 hour flight. There's a 25 hr layover in Toronto -- fortunately my sister lives there so i'm going to stay the night with her. Otherwise I don't know what they expect their customers to do -- I guess sleep on the floor or cough up another 100 bucks for a hotel room in TO.
Best programme without a doubt for BA is AA -- low season = 42,000 miles to North America return, high season = 60,000 miles. (At least for the moment).
