The question comes with a qualifier, which in this case is unspoken - that gasoline remains in plentiful supply. If the condition now changes to one in which gas is in very short supply nationwide, and/or has become extremely expensive, then none of the afore-mentioned bikes would fit the bill. This is not an unlikely scenario either in the not too distant future, and the fact that one is contemplating riding a bike across the continent instead of driving an SUV could be taken to mean that fuel economy is a factor. In such a scenario, without prejudice or favoritism, I would choose the very bike that I currently have - the Ninja 250, the smallest bike that is highway-potent, with its 75+ mpg fuel economy (possibly 80+ mpg with a 15-teeth front sprocket). I wouldn't do it for fun, but if having enough fuel to finish the trip and get to my destination is the prime concern, then the Ninja 250 would be my choice.
