First "get away" in Americas planning

[AnjinSan]

Hi,

I am from Europe. So far I've only traveled by motorcycle on my continent. I am planning for a longer trip with my bike in Americas (rather ambiguous but I will explain below).

The things I will have to work with:
- approximately 6 months of leave from work. Could be a more could be a little less.
- starting date is June or July 2012.
- I will be traveling on a DL650, 2up with my wife (yes, not only she likes motorcycles but also wants and supports this big "go away trip" )
- no "required" destination or place to see. We want to remain flexible in planning the trip ( hence asking for help here)
- the budget would be rather tight. I would say around 14k so far. We will have to rely for sure on CS, free camping and so on in order to stretch the cash as much as possible.

The ideal option would be to :
-fly to N.America, go to Alaska, then go all the way down to the tip of Argentina.

Now, the (rather general) questions:

Big question is:
Would 6 months suffice for this? I do not want to be in a hurry but I also do not want to spend weeks in one place.
For Europe 6 months could be an "eternity" (meaning I could travel all over the continent and plenty. It would also be very expensive... But Americas... I have no idea

So presuming I would have 6 months, should I try to reach for the whole "way down" or should I just settle for N.A. C.A. or S.A.?

- for example, since I do not have a lot of cash, it would make more sense maybe to just fly to S. America. This should be cheaper once I get there ( from what I've read here) but on the other hand shipping me and my bike there and back is more expensive than shipping to N. America.

Second big question:

- should I be worried that my time frame (6 months starting in June or July) is not the best time frame for Central America and S. America?
What would you advice regarding traveling in august for example in Central America? Is it doable/enjoyable by motorcycle or is just very veeery wet ?

I realize that my questions might be "basic" for more seasoned riders on those parts of the world. But, taking in consideration the details I've provided at the beginning, what would you advice?

Thanks!