i live in cornwall, right down in god’s country west penwith, i agree with many who’ve already said it newquay can be awful.
thing is though that the whole of cornwall is totally different, east to west, north to south. and the lizard is different again. i love the lizard. a huge generalisation is that north coast is cliffs, the middle is high hills and the south coast wooded valleys. beaches are everywhere. take your pick.
if you want typical seaside town stuff then newquay and perranporth and bude will do. if you want more refined then st ives, mousehole etc. if you want local penzance/newlyn. if you want to get away from it all look on a map. its all possible.
best place of all is sennen cove, but i’m biased as i have a house there… http://www.littlebeachhouse.co.uk – hows that for a shameless plug! ; )