Since you're such a band of stand up chaps I thought I'd share this resource I happened across. CalClassic Vintage Propliners, Sceneries and AI Traffic for FS2004
Now FS2004 is a little dated and some of the modules reflect that but, this site holds the keys to Valhalla if you're looking to turn an FS2004 install into an immersive retro civil aviation sim. I've installed the entire package according to the instructions provided at this site and it has not only provided me with a relaxing platform from which to improve my virtual airmanship but it has kindled in me an interest in flying again that had been left starved outside of my WoFF experiences. The package mainly focuses on late 1950's to early 1960's propliners. The resources at CalClassic provide an atmosphere conducive to re-creating all sorts of vintage routes, including historically significant ones, without immersion breaking boring metal tubes sucking and blowing and generally getting in the way of your flights of fancy.
It's a long process to get it all up and running but not so demanding that the average WoFFer who is familiar with modding shouldn't be able to handle it.
Also, if you want to go that extra mile (and I know some of you will) here's a site that contains a resource of vintage to modern-ish airline routes. I've found it very helpful in lending that little bit of extra "authenticity" to my flights since following these historical routes and ending up (usually) at historical airports with fitting scenery and traffic just makes the trips that much more satisfying. Vintage Airliner Routes
Finally, if you feel so inclined, pop this on in the background for extra immersion......... Ye Olde Timey Radio
Hope you enjoy it as much as I have