I've checked out the roads available on pashnit.com in California; you guys are in Nirvana there. I'm awe of the great roads, both in the quality of surface, lack of traffic (if chosen carefully) and twisty bits.
I've got a Guzzi buddy in England and some of the rides he does, say from shore to shore, would barely get me out of state. Montana just recently passed the million residents benchmark has an area of just over 147,000 square miles. Germany is just under 138,000 square miles.
There is a LOT of "empty" space in Montana and when you consider it is surrounded by Canada, North & South Dakota, Wyoming and Idaho, all rather low density areas the mind set of travel is completely different.
Back to my map, the Datil New Mexico rally is about the same distance, very roughly for me as riding from Lyon to Milan. I consider that a fairly short ride. The recent Not-A-Rally was a bit less than Lyon to Grenoble.
Toss in Australia, looks huge on the globe but is smaller than the US, west coast to Cleveland Ohio about the same distance as west coast to east in Australia.
I find it a fun exercise to find an equivalent ride in the US when folks describe their great rides.