postman said:
May want to go to Mablethorpe next summer.
....... try to give me a couple of nice routes from here in sunny Leeds.
May have 3-4 days to myself.
Leeds-Mablethorpe is certainly do-able in a day, but it would be 100 miles+ unless you go direct and that isn't a particularly interesting route.
If you have the extra time, I would go flat one way and hilly the other. The flat way would go from leafy Meanwood, Swillington, Fairburn, Beal, Snaith, Airmyn, Howden, Gilberdyke, North Cave, South Cave, Roman road to Brough, over the Humber Bridge (worth it at least once), round the coast through the industrial heritage of Immingham and Grimsby, the very quiet A1031 to Saltfleet and on to Mablethorpe.
Hilly route would go south through the west and south Yorkshire coalfields (west of the M1 more scenic than east, but a fair bit hillier), head east from Rotherham, cross the Idle at Bawtry, Gainsborough, Market Rasen, Louth, Withern, Mablethorpe. You would have to jiggle about a bit to avoid the main roads which I suppose could be full of shed-draggers in the summer.
All this fits on the OS Northern England map, which has plenty enough detail for cycling.
If you wanted you could always get a train to Sheffield or Selby to cut out some of it, but I think it would actually make quite a good circular ride. You could go out through Beeston to Grimesthorpe (Sheffield) and back via Grimsby - grim, grimmer, grimmest.