Skudupnorth, we must have cycled past where you stay many times, and ColinJ, the ride around the peninsula via Penzance, Mousehole [Raginnis Hill out of there is fun], St Buryan, [miss out Lands End, it's now rubbish] St Just, and ride the coast road back to just before St Ives then back over the tops and down to Hayle, just tremendous.
Raginnis Hill is my nemesis - I have not been able to get up it without a stop. The road from St Just across Sancreed Beacon and down to Drift Reservoir is worth inclusion in a ride, as is the cafe in the middle of nowhere near Ding Dong mine.
Here's Raginnis from my bar cam (ouch):
and by way of compensation, a less strenuous walk near Porthcurno: