I'm also a New Englander. I rode 800 miles of the Pacific coast south from Tillamook, OR down to the SF bay area in 2019. I only have three things to add here.

The road generally is winding with much higher speed limits than we have here in the northeast. And there's no room for bicycles on much of it. I found this nerve wracking. Conditions that matched roads I would never ride here in central MA, like 202 down the west side of the Quabbin.

Also, for some reason, many CA drivers won't cross a double yellow line to pass a bicycle -even when they have visibility and no one else is around. A cop told me you can't break the law to follow the law (cant cross the line to give the require 3 feet) He also said he himself would never enforce it in that situation. It's strange and slightly anxiety-inducing to have a line of cars behind you going 15 mph for no good reason. I eventually adopted the practice of just getting off the pavement to let them by.

You will encounter many, many other bicycle tourists doing the route. The great majority of them will be heading south. But the CA and OR state campgrounds have really nice hiker/biker sites that will always have other riders in them. This may be a positive or a negative depending on your interest in comradery.
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