You are right on EFB, it doesn't display the airways due to the way it was intended to be used. Not so much for the actual route planning, more for the route display. Sounds a bit clumsy first, but makes sense. The intersections are all present in the data though, you just don't see the lines as there is no real planning stage.

For paper charts, the Ebay tip is a good one. Same for the free opportunities on some countries, unfortunately not worldwide. For the rest, maybe search the old FSBuild releases, being freeware. I don't know if they support FSX though. Newer releases are payware and do support FSX of course.

For my airliner flying, I mostly import routes and then modify them in EFB. For the self planned ones, I still have good old Flight Sim Commander, but that's payware. It shows you the airways. I think Mark uses that one too. As said, for lower altitude flights, the freeware Plan-G lets you click-build plans, but that modern airliner stuff doesn't happen there.

What I've left out are those free and pay websites for the planning, not only route listings (which are mostly free). Those sites offer subscriptions of some kind and then allow to view actual charts or something. I haven't tried them, but just 'flew' over some of the advertisements. Maybe there's a trial period somewhere.
My memory is weak, I can't recall the name of some payware service I read about on some occasions.

Here's one I haven't tried. Just as an example. It's free I think. http://www.virtual-dispatch.net/?page_id=405
Mind the tips from the other folks since e.g. SkyVector allows at least for US planning, for free.