What's the parking like in St Ives? I got the impression it wasn't that great when I was staying there a few years ago It is very nice though, steep hills aside. The countryside around St Ives is lovely.
Wales wise, what about the Gower Peninsula? That's supposed to be beautiful and I shouldn't think it would be that bad a drive from Cornwall, at least you'd have a fair bit of it on motorways.
Kendal is a good shout and personally I really like Carlisle, though maybe it wouldn't be a very good base for exploring the Lake District. Maybe you could explore some part of Hadrian's Wall.