It is hard work, but i loved the Torino-Nice rally, you can take variations on the route to include more/less off road, but the high gravel passes of French/Italian Alps and bivvying in the old Napoleonic forts on route.
I have had some great bikepacking trips in Belgium – this was great – https://bikepacking.com/routes/ardennes-arbalete/
I hit 50 next year and am looking at a variation of this route, liking the idea of gravel roads, linking up small micro-breweries – https://bikepacking.com/routes/appalachian-gravel-growler/
Also, having watched TdF this year, been looking at a long weekend hitting the gravel roads of Champagne region of France