Tinners way - St Ives towards Lands end - this avoids the coast but you get coastal views - you can return on any number of paths start and finish in many places.
there is an excellent walk from Bosigran carpark north of St Just. - near the old tin mine - Rosemergy on the map- which can then take in the prehistoric sites of Maen an tol, Nine ladies stone circle, Chun Quoit, Chun Castle, loads of other standing stones. I think there is a guidebook which links ancient sites in shortish (<10mile) walks.
Just get a map and plan - if you keep off the coast you will be unlikely to meet and long drops.