Would double plastics be necessary?
Not unless you are ice climbing. Almost all of the standard routes on 14ers wouldn't require plastic boots. Something like Sorels or Bugaboos is what I bring on the standard routes because I don't like rock scrambling in my plastic boots and I don't find them as comfortable (most 14ers require as least some rock scrambling or walking on rocks up high because the wind scours off the snow). Of course, some people I know do use plastics for snowshoeing, but it isn't required.
In Colorado, plastic boots are more for ice routes (waterfall or alpine).