The ACA has an excellent array of maps for the growing US network of cycling routes, and Québec's Route Verte remains a brilliant example of How To Do It Well.
Other than the Great Divide Route (which runs north-south along the Rockie Mountains), all those ACA routes are on highways and poorly thought out, in my opinion. For example, the ACA route crosses nevada on highway 50, which is a two lane highway with rumble strip extending across the entire hard shoulder (to wake up drivers who doze off while driving and veer into the shoulder) so you can't bicycle on it, which means there is danger of squeeze situations (trucks in both lanes, the truck behind you can't slow down due to going downhill, so the bicycle must get off the road onto that miserable shoulder). So you have to be looking in the rear-view mirror constantly. Very stressful. The scenery is fine, but you can't really appreciate the emptiness of Nevada because of all the traffic whizzing by. Worse, most of Nevada is open range, meaning no barbed wire fences EXCEPT along the really busy highways like highway 50. So you're jammed into this narrow strip of highway with lots of noise, a shoulder that you can't ride on, boring strip of asphalt in front of you. Maybe if you're from Europe you're so excited by the vastness that you don't notice all these issues, but my standards are a LOT higher. And yet all you have to do is venture off highway 50 to one of the many dirt roads and all of a sudden everything changes. No noise, no traffic, no barbed wire fences, thousands of square miles of countryside all to yourself, plus it's dry, unlike most of the places with no people in Europe (northern scandinavia, parts of scotland and iceland), which makes bicycling a lot more enjoyable. I have a guide to the dirt road route across Nevada (part of the American Discovery Trail) on my website:
http://www.frankrevelo.com/hiking/dest_us_nevada.htm. Yes, it's a little challenging due to lack of resupply points, but most of the difficulty disappears if you have a bike like the expedition-level Nomad MK2 (Mondial tires, Thorn racks, Andra CSS rims), plus 4 ortlieb panniers, so that carrying huge amounts of food and water is no longer a problem. Andy Blance has done a really good job designing and field-testing the Nomad so that touring in places like Nevada is no longer difficult.
The other ACA routes are also bad, because they are almost all on paved roads. The assumption behind the ACA routes is that bicycles belong on paved roads, and that paved roads are good because they allow you go faster and this is good because you don't really enjoy touring, you just enjoy telling everybody afterwards about all the famous tourist sites you visited, so the faster you get the tour over with, the better. I have the opposite view, namely, that the natural place to bicycle is a dirt road, away from all the motor vehicle traffic, and that paved roads should only be used when there is no dirt road. Also, going fast is not my goal because I actually enjoy touring for its own sake.
As for Australia/US, what I mean is that there are places in the world where a dirt-road bicycle (like the Nomad) really comes into its own, and Australia and the western United States are two of those places. Argentina, savannas of Africa, and steppes of central Asia similar. Note that all these places are associated with horses (or zebras in Africa, since the sleeping sickeness and other diseases kill regular horses in Africa). Europe has plenty of dirt roads, but there no NEED for a bicycle to get around in Europe. You could just as well get around on foot, and that's actually what I prefer to do in Europe. By contrast, in the places associated with the horse, getting around on foot is next to impossible due to the huge distances involved between towns.
[edit: fixed lots of spelling errors]
