In reply to Tom Valentine:
Lots of lovely choices. For example:
From St Ives you can walk out along the coast path, then back through the fields.
Bus to Zennor then back along the coast path.
Drive to St Just. Walk from there to Bosigran, then bus back (go to wherever the bus actually stops). Or walk to Sennen, then bus back.
From St Ives to Mousehole the whole coast path is lovely. You can't go wrong whichever part you choose.
Walk out to St Erth, past Carbis bay, where the G7 was held, then take the train back.
Post edited at 20:20