Pedn Olva is bloody lovely and worth a look.
A lot depends on when you are going ? Quite a few of the holiday cottages do weekend/midweek breaks off season, Aspects holidays is one of many cottage companies operating in the area, I only mention them because I have used them quite a lot and have only had good experiences with them.
Downlong cottage offers B&B in a brilliant location, very easy walking distance to all the beaches/harbour/town etc.
The Sloop as someone else has mentioned, great pub, nice rooms.
If you want to go cheap as chips there is a Premier in nearby Hayle or the new one on the harbour front at Penzance and if you are driving there it is only a few minutes from the park and rail stations at St Erth or Lelant Saltings.
Hayle is a great little town so it might be worth looking there too, or Penzance or Marizion, if you don't mind a little drive to St Ives ?
Not going this year and madly jealous you are 