The classic traverse of High Street, no contest.
Park at Brotherswater, ride/push/carry for 2000 ft up to the top of High Street, enjoy superb airy riding on the Roman road along to the monument on Thornthwaite Crag for lunch, double back and ride all the way gently descending towards Pooley Bridge then turn back along the shore of Ullswater for a tough technical ride back to the car. About 26 miles, 4500 ft of climbing, miles of superb downhill on ace singletrack and your body will ache for three days (mine has just stopped aching after Sunday!)
Email me if you want to see the route and some photos.
reedy at orchardhouse dot fsworld dot co dot uk