Jeff, thank you for that very useful data chart. Exactly what I was looking for in terms of long-range planning. I'm also planning an extended trip through LatAm and beyond.
So, regarding Latin America, to me it seems like the four factors dictating favorable riding weather are
1) Avoid the rainy season in Central Am, May-Oct
2) Avoid riding the Andes' passes in winter, Jun-Jul
3) Avoid the Amazon's rainy season, Feb-May
4) Try to do Ushuaia from Nov-Jan
So, how does this sound:
Depart the US around September, get to Colombia by Jan, head down to Bolivia by April, cross into Brazil, get to Buenos Aires by Aug, slowly work down to TDF by Nov/Dec and end back in BA to ship out by Jan (onwards to Europe and Africa).
Things I'd like to time appropriately: seeing the salt falts not under water, not riding Amazon in rainy season, spending good time in Andes high altitude, favorable TDF trip.
I've adopted the mentality that 'the slower you go, the cheaper it gets'