We stayed at Tregenna Castle July 2008 for one night in a family room. It was quite nice. The facilities are great. Indoor pool, outdoor pool, tennis courts, gym. The location is stunning, overlooking St Ives harbour and the sea. Gorgeous. We are returning for a week at the New Year, staying in a self-catering cottage.

We stayed there by chance when Cornish Gems (referenced by another user/reply here) put us there when there was a problem with a cottage we booked thru them. We had a VERY bad experience with Cornish Gems and would not recommend them to anyone. The house we booked was a disaster, literally. We ended up in a nice cottage 2 days later in Lelant Saltings which was near the train station. But our holiday was greatly disrupted and there was no compensation for our trouble. No real apology either.

Anyway, St Ives and the area were great and we are returning to Tregenna Castle which we expect to be a good experience.

Good luck.