Booking lodging along the west coast of USA

As in Europe, in the USA it does depend on your mode of transport, your willingness to find alternative travel options, the actual place you will be at any given moment and how flexible you are in what kind of accommodation you are accepting.

If you travel by car, book online a few days ahead of time and are flexible in your length of travel day, and are willing to accept a wide range of accommodation, you do not need to worry at all.

On the other hand, if you travel by train or long distance bus and you will only have one or at most two options for travel per day and not a lot of flexibility, and you are picky on the kind of hotel you stay you better make sure you have a kind of lodgings you are happy with before you are stuck in a town with no alternative and no transport out.

Most people will be somewhere in the middle. But the general rule is, when you have more options to get to a hotel somewhere else, you need to worry less to book ahead. Outside of local holidays and popular weekends, with a car you hardly ever even need to book ahead, as long as you are willing and able to stretch your day by a bit and have checked out there are enough hotels/hostels/campsites with cabins or whatever you find acceptable within reach.

If you travel by 'once a day' transport, like trains in the USA, you better make sure a hotel (or whatever) holds space for your arrival, but in many cases booking a few days ahead will do.

You'll be traveling after most schools' spring breaks end. A few universities may finish their spring semesters in early-to-mid-May but that shouldn't cause too many problems.

There are no federal holidays in that period either.

This strongly depends on where you are going, what kind of accommodation you are looking for, and how much you are willing to pay.

The West Coast of the USA ranges from National Parks and wilderness areas to some of the largest urban areas on the continent. In popular tourist areas with limited accommodation, such as the Big Sur, you may well be too late to book anything for your trip 3 months in advance.

When we vacation in North America, we typically try to book our stay 5–7 months in advance, but we book refundable accommodation. In some places, even nearly 6 months ahead is too late and we cannot be sure to stay in our preferred location. If closer to the date it appears that accommodation does not sell out at all, we may cancel our bookings allowing for a more flexible schedule. If it shows that accommodation does sell out, then at least we will have a place to stay in our preferred area.

(In my experience, in Europe none of this is necessary as one can almost always arrive at a campground unannounced any time of year anywhere in Europe. This may be because in popular areas in Europe, there are many many campgrounds, the French Ardèche region probably has thousands of them. The density is far lower in North America. Similar is true for cabins; Europe has lots of semi-deserted rural areas with a surplus of accommodation, this is not true in western North America, although I've found it to be somewhat similar in Newfoundland, which is the only part of eastern North America I have relevant tourist experience with.)