I did a route a year or so ago, more or less self-made. Trans-Lancs. Started in Rochdale, up onto Rooley Moor Road and then it used bits of Mary Townley Loop, Trans Pennine Trail various bridleways and another old drove road (Salter Fell) to take me right acorss the county of Lancashire. Finished at Arnside on the shore of Morecambe Bay, just in Cumbria. The latter third used a lot of roads actually, I did the ride on my CX bike., it would have been really annoying to do that on an MTB.
For me it was just a way of doing a nice all-day ride with something a bit different – Lancashire changing from the mill towns and industry of the southern end up through the livestock farming in the middle and to the more touristy bits up by the coast. Really enjoyable.
I’ve got a similar route in mind across the Lake District starting down in Barrow and finishing at Gretna Green to go right across Cumbria. I like ways of adding a “story” to the ride.