Calella - Llafranc is 15 minutes on foot on the coastal path.
Calella - Cap Roig Gardens, heading south, takes about an hour.
You can walk to the beach at Castell, passing other beaches and Iberian settlements nestled among the pines. To Castell takes about 2 hours and a bit going leisurely.
Famous for the singing of 'Havaneres' in July, when you definitely won't find a spare rock to sit on. This blogsite has some lovely music, postcards and photos of Calella.
At the same time as listening to them, you should be burning rum on the beach (alas, no space).
Here's a look at the festival of music and dance in summer, held at the Cap Roig Gardens
Here is information about visiting the gardens