Cornwall
The coastal path around Cornwall, which we walked as the South West Coast Path between 2007 and 2011, is massive. It's about 290 miles, with lots of ascents and descents, and it took is 28 days of walking, spread over five holidays. It was also rather special; it was on our holiday in the extreme west of the county in May 2007 (our first holiday on the South West Coast Path) that we fell in love with the coastal walking in this county. When we entered Cornwall from North Devon two years later, it was slightly away from the coast because of horrendous weather (though we returned in September of the same year and crossed into the county by the "proper" coastal route). By the time the Cremyll Ferry whisked us from Cornwall to South Devon in May 2011, I was so emotional that I was just about in tears.
In detail, the legs in this county, described in an anti-clockwise direction, were as follows:
Between the North Cornwall Border and Padstow (May 2009): Hartland Quay (Devon) to Bude; Bude to Crackington Haven; Crackington Haven to Tintagel; Tintagel to Port Isaac; Port Isaac to Padstow.
Between Padstow and Lelant (June 2009): Padstow to Constantine Bay; Constantine Bay to Porth; Porth to Perranporth; Perranporth to Portreath; Portreath to Lelant.
Between Lelant and Penzance (May 2007): St Ives to Lelant and return; St Ives to Zennor; Zennor to Cape Cornwall and St Just; St Just to Land's End and Porthcarno; Porthcurno to Penzance.
Between Penzance and Falmouth (April 2010): Penzance to Porthleven; Porthleven to Lizard: Lizard to Coverack; Coverack to Helford [and Landrivick Farm]; [Landrivick Farm and ]Helford to Falmouth.