Barcelona to Cinque Terre by car (what to see)
 

We will be traveling to Barcelona in mid-May, staying there for a couple of days, and then driving along the coast of France into Italy, where we'll head to Cinque Terre (ending our trip in Florence). I know very little about the coast north of Barcelona or the southern coast of France, but we are interested in stopping in little villages, seeing interesting sites (architecture, markets, wineries, etc.). We are less interested in the glitz and glam of the Riviera. So, question 1, where are interesting villages/towns one might like to stop for a visit or even stay a night or so? And, question 2, do you think we need reservations for accommodations along the way or, in mid-May, is it likely that we can locate accommodations as we go (not pinning ourselves down) and still get decent choice among AirBnB or mid-range hotels. Any help you can provide would be VERY much appreciated?

How long do you have for this trip?
Where are you coming from? If you will have any jet lag at all, you might want a bit longer in Barcelona, at least two full days, not counting arrival day or departure day, would be minimum.

Have you checked for drop off costs of car in a different country? Check highways, tunnels, tolls, driving times.
If you are already in Europe and own a car, or are doing a lease/purchase, a long car trip can make sense. Otherwise, it might make more sense to pick one area to visit where a car would be great for leisurely sight seeing, and use trains or planes the rest of the time. Example: take train from Barcelona to someplace near the coast in France. Rent a car for a week or so in France. Turn the car in and fly from Marseille or Nice to Florence or another city in Italy. Use trains in Italy because they are easier, cheaper, more relaxing.

They will likely have changed, but have you checked Covid protocols from Country to country?

Do you have any idea at all of towns/villages or sights you wish to visit? Any activities you wish to do?

In May, I would want to have hotels booked or several picked out in places I might stay, so as not to be using a lot of travel time trying to find a place last minute. We used to wing it, but now a days, so many people do book ahead, that you may be left with the worst lodgings (and just as expensive) last minute. It started happening to us and it was really annoying to realize we were paying top dollar for miserable lodging when we could have had something nicer for less if we had booked earlier.

For the France portion of the trip you might consider using the hotel chain Logis de France. We have used them a bit and you get a hotel that is comfortable enough (quality varies), but always an interesting restaurant. They are usually not in cities but in interesting rural locations or villages. We have had some very nice surprises that way. Going from hotel to hotel this way would be a good trip across France. https://www.logishotels.com/en/

Lavandula

You do not have to reserve anything in France, even in the height of the tourist season, and certainly not in May. You will have complete flexibility by car. The Cote d'Azur is only a small percentage about glitz and glam, both of which can be easily avoided. In three trips for me, I've never seen it, expect for a brief stop in Monaco.

Catalonia stretches across the Spain-France border with Barcelona and Perpignan as its twin capitals. Colliure is a gorgeous beach village that features Catalan architecture. Perpignan has the Palais de Rois de Majorca. Marseille has a dramatic port with scenic boat trips. Les Calanques are rocky fingers jutting out into the sea with great short hikes. Aix-en_Provence is the former Capital of Provence with many small fountains (and the stunning Fondation Vasarely), Biot, St Paul, Cagnes-sur-Mer all feature important museums and locations for the world of modern art. Villefranch-sur-mer has the rue obscure from a distant past, and Menton is the home of Jean Cocteau, a museum located in the fort and a beautiful old town. Tons more than I can even mention, but I am sure others can fill you in..