As gleaned from books and Wiki, the Oregon Coast Trail runs between 425 miles, or 382, depending on how one chooses to hike it. The wonderful thing about Oregon and it's coast is that beach areas are all public land thanks to the Ocean Beach Bill of 1967. You can't own the beach in Oregon and I think it should be like that everywhere! It's the ocean damnit, she can't be owned!
The trail begins at the south jetty of the Columbia River, about 14 miles from the quaint town of Astoria. It ends at some unmarked section of beach on the California/Oregon border somewhere south of Brookings. Much of this trail is on paved roads (boo!), old jeep roads, actual trail, beach, and sections along the shoulder of the dangerously scenic Highway 101. Hitching a boat ride is recommended at bays and some wide river crossings. Hitching is also recommended on some sections of 101. Hiker/biker camps are scattered here and there along the trail and if need be there is motel or hostel lodging here and there as well.
As pointed out by Bonnie Henderson (she writes a great blog about this trail too) who wove in a guide to thru-hiking this trail (a thru hike is completing one long continuous trail) in her book Day Hiking the Oregon Coast, this is not a wilderness experience. Urban areas will become sparse as one reaches the southern coast, but you are never far from 101, a town or a road on this trail.