I heartily recommend The Top House session at The Lizard... and the Cove Inn session in Cadgwith. Cadgwith also has something going on Fridays (the "Fishermen" continue what they have been doing for decades at The Cove Inn). Gunnard's Head is not bad -- primarily a jam session with a Celtic flavor. The Fountains -- mid way between St Ives and Penzance used to have a singaround on Wednesdays I believe.

Try my aunt's B&B (Rosevidney Farm, 2 miles out of Hale on the road to Penzance and Marazion) for a nice stay ...

Cheers,

Brian