In the spirit of Rae's idea, I would be happy to travel.. perhaps next year with all the current crap going on. Count me in!
(you'll need a -free- MRA account to view the routes, I am afraid ...)
The first one, the one I'd call the "Flanders Fields" ride,
https://www.myrouteapp.com/routetrack/open/3599261 is a 4 to 5 hours (round-trip) ride I also used as the base of a ride I helped organise for a Flemish biker forum. A calm day's ride of around 200 km. Every year, I ride a variation of this route which passes along quite some WWI places of interest. To mention some of them :
- the Irish "peace park" in Mesen (Messines might ring a bell better)
- a pass in the vicinity of the "Dodengang", a frontline where soldiers of the former opposite sides could see the white of each other's eyeballs, creepy to imagine,
- the lock complex (correct English I hope for the Flemish "sluizencomplex") in Nieuwpoort from which quite a surface of the WWI battlefield was flooded
- quite some military graveyards of different WWI Allied Forces (one of which is Tyne Cot),
- 2 of the 4 German WWI graveyards in Flanders, one of which might ring a bell by mentioning the name "Käthe (Kate) Kolwitz", a German female artist of whom a very expressing statue of a parent couple mourning their (own) son lost in the war is present on that graveyard (in Vladslo)
- the crash field of Guynemer (a French WWI air hero) and a pass along the stork statue pointing in that direction - this could "Ã la limite" be extended to include Von Richthofen's (a German WWI air ace) crash field in Wervicq-Sud (France), located close to the Belgian-French border. As a former Air Force man, I was keen on looking up both of these locations quite precisely.
- a pass through Menin gate (de "Menenpoort") in Ieper... not at 8 o'clock in the evening, though... you may know exactly why
And then
https://www.myrouteapp.com/nl/info/route/3599262which is a "heavier-loaded" day's ride (500 km, about 8 hours of non-stop riding). Can be shortened a little if desired. Whenever I have a full day of free time and the weather forecast is good, I ride my next iteration of this ride mostly along the Northern-French country roads. At nearly every new iteration (I just rode my second iteration of this year last Tuesday) I exclude roads which are less to my liking, and include roads which I think are better suited to my desiderata, which are : to be able to ride roads as far as possible free of civilisation (villages, cities), and hence as much as possible free of the speed traps coming with it. Apart for some 100 km on highways, at the exit, I'm immediately in the fields for the better part of the trip.