Tom__'s Strida is a MAS (that means two speed) and it is retrofitted with 18" wheels,
this version has (in the high gear) exactly the same gear ratio as the 18" EVO.
I’d suggest you read something about the “small wheel vs large wheel” discussion,
the following links might be interesting for you:
Source: http://en.wikipedia.org/wiki/Small_wheel_bicycle
Source: http://www.bikeforums.net/archive/index.php/t-524435.html
Source: http://www.theguardian.com/notesandqueries/query/0,-200758,00.html
Source: http://cyclingabout.com/index.php/2011/12/700c-vs-26-inch-wheel-size-for-touring/
For my money, it would be (for your planned high distance rides) advantageous to choose a bike with full size wheels - because comfort will be an important criteria - if it has to be a folding bike, maybe something like this: