We stayed at the Polmanter camp site in St Ives which I would recommend, it has great facilities including a swimming pool which we used every day. We visited a lot of different places; Newquay, St Michael's Mount, Truro, Penzance and Lands End - and of course I couldn't resist doing a spot of charity shop shopping while we we there. I really enjoyed going to St Michael's Mount, it's a castle built on top of a small island which you can walk to at low tide. We arrived a bit early and the path was still under water - the sea was icy cold and I couldn't feel my feet by the time I had crossed!
I think the only downside that I can think of was that the weather was so good that our tent was like an oven by 7am in the morning so we woke up really really early every day. That and the sunburn!
We were definitely not put off camping and have already been planning some mini camping breaks before the end of the summer, I am thinking maybe Whitby, where would you recommend?