Hi,
I'm in Utah at the moment about to head south to Mexico,

having travelled about 12500 miles in Canada and USA, I say about 12500 miles because a crash in Nova Scotia took out my speedo and I didn't get it replaced until Calgary
I'm at the opposite end of the age scale to you guys,

but that makes little difference apart from having been exposed to 'social conditioning' for longer. You know the sort of thing....motorcycles are dangerous and anywhere but home is lethal with all those 'foreigners' wanting to kill you and steal your money.

I get advice about Latin America almost every day here ranging from, 'I wouldn't go there alone' (the foreigners are out to get you) from people who have never been; to 'it's great you will enjoy it' from people who have been. Go figure!!! I know who I trust, and it's not the people who have never had a passport.
The reason for the above observation is that it figured in my choice of route, 'let's start where the natives are known to be friendly and I speak the lingo.'
So I elected for trans Canada first, then head south until I fall off the bottom into the Antartic. Shipped the bike by sea to Halifax,NS, for about 600quid, from Southampton, drove it to the docks,

met it in Halifax

and drove out of their docks, easy

(I love these little guys)
But the weather is a big factor, it is no fun riding all day into rain, snow and windy weather

. I have fortunately only had a very little of each and the cold gusty wind on the high prairie here is no fun, plus some of the towns have few occupants, one I passed through had a town plate either side of a single house, guess the population must have been 2.:confused1:
Canada is more expensive than the USA for motels, but there are many good campgrounds in National and Provincial Parks, although many do close from October to June. Fuel is a little cheaper than the UK in Canada, but only £1:50 a gallon in USA

but only 91 octane at best, so expect higher fuel consumption.
So first I would look at the weather you will meet coupled with the country you will meet it in. Snow in Europe is not like snow in Canada, with upto 190 miles between towns and massive snow falls
Plus you will need to check out the political situation, a friend is in Greece heading for Turkey then Iran on his way to Australia, hmm may be a problem there?
Also consider that it is the start of spring now in the Southern Hemisphere, so can you ship maybe to Argentina, come north in time for next summer in North America before shipping south to Australia or SE Asia next winter? or visa versa
The world is our oyster, it's just that I don't fancy frozen oysters.
Sorry if this seems a bit of an obvious reply, but I reckon if you do just a tiny bit of homework (which is exactly what you are doing on this forum) it will make your adventure the fantastic thing you hope it will be, and the fantastic thing I'm enjoying right now
Mexico here I come