If you’re not going racing – consider going NoBo (North Bound)
Starting at the south will be warmer yes, but you’ll finish up in Canada at Banff and get to chill and relax and enjoy it up there. Otherwise you’ll be finishing at a border checkpoint after a 100mile road section. There is nothing there. Be prepared to turn back around.
Historically the route is raced SoBo – but people do also do it NoBo. I’m still undecided for this year.
If you want info, the historical threads on bikepacking.net are the place to get all you need and more.
ACA book and maps will cost you about £100 delivered. THey are worth it even if you are just wanting to take a look at the route for yourself and potential ideas. If you’re lucky, you can pick up the last print set for cheaper – I’ve sold mine on that way.
If you want to read about the race/tour from peoples persepctive grab a few copies of the Cordillera – it’s not cheap, but there is a reason for that – it goes to the education fund for a racers daughter, Dave Blumenthal, who died on route: http://tourdivide.org/blog2010/memory_dave_blumenthal
Also, Jenns article is a good place to start – issue 67 I think?
Also Johns: http://singletrackworld.com/2015/01/throwback-thursday-riding-the-great-divide/
Alternately, there is so much good info out there now so just use Google 🙂