Both A and B walks start at Bolton Abbey and end at Grassington.

The A walk goes via Simon's Seat and Langerton Hill (the blue route on the maps).

14 miles with 3000' of ascent Map N Map S gpx download

The B walk follows the River Wharfe (the red route on the maps). There is a pdf describing the route here.

10 miles with 1100' of ascent Map N Map S gpx download

There is a shorter (7 miles) route from Grassington to Burnsall and back described in this pdf.