Solo Portugal trip

Portugal was my 1st European country I went to as an adult with my teenage daughter. People are friendly and, in my opinion, it's an easy country to do yourself. When I returned with my husband, his 1st time in Europe, we spent our time in Porto, Minho region, the Silver coast, and Madeira. Then returned later that year to spend a week in Lisbon and Evora.

Madeira is gorgeous, but not a beach area.

The high speed train is a great way to connect Lisbon, Coimbra, and Porto, cities you would not want a car.

Personally, I love the Minho region, north of Porto. If you plan to spend time there, or the Silver Coast, I would recommend a car for that part of the trip.

I've attached a link to the Julie Dawn Fox blog which is a great resource regarding some of the smaller towns in Portugal. Rick Steves book is very limited when it comes to Portugal.
https://juliedawnfox.com/

Both Lisbon and Porto have a lot of street art. Can just wander around and find it. Or google and there are many articles regarding some of the more famous ones. Pretty much it's everywhere. My favorites are Perspéntico by Ligen and Half Rabbit by Bordallo II.

Portugal is known for its azulejos or tiles, especially blue. In Porto, the São Bento Railway Station is a great example, and if you choose to travel by train, you will get a chance to see it when exiting.

I recommend Lisbon, Evora, Alcobaça, Coimbra
and Porto. Alcobaça should be seen but not necessarily for an overnight. We especially liked the Cathedral there.

We stayed in the Pousada in Obidos which we liked. Obidos was ok as a base but the town itself is good for a few hours at most. We went to Sintra as a day trip from Lisbon by train. We preferred the more historic National Palace over Peña Palace which attracts hordes of tourists.
We always rent cars for flexibility and we visited small towns and found wonderful pottery on back roads.
We rented an apartment in Lisbon but recommend the Quinta de las Lagrimas in Coimbra. We stayed in the Pousada in Evora and loved it there. Enjoyed the Pousada in Obidos which has great views and a wonderful dining room. In Porto we enjoyed The Infante de Sage's hotel.
Portugal has the kindest people we have met anywhere.

Traveling solo in Portugal is very easy. I moved here solo and have had zero problems.

The trains to the main cities are easy and inexpensive. The smaller towns are a different story. As stated earlier, if you want to visit the Silver Coast, a car is recommended. But, Lisbon, Porto, Evora, Coimbra are all easy on the train. Btw - driving in the middle of the country is quite easy. The expressways are good and quite empty. The smaller roads are good but tend to be winding.

Dramatic beach towns - fairly close to Lisbon are Ericeira, Peniche, and, Sesimbra. All of these would really require a car IMO. The Algarve has a number of dramatic beach towns but not a lot of art and the other things you mentioned. The Douro valley has dramatic views even though it’s river instead of sea.

Lisbon and Porto is where you will find the most concentrated art. As mentioned, the tiles are ubiquitous and stunning.

Barcelona would require a flight and really rush your time both places.

I’ve done a few Airbnb experiences and have been pleased.

Dress is quite casual. Having shoes with good grips and very comfortable is likely the most important thing to wear. You will be walking on cobblestones most of the time and they are hard on the feet - and slippery when wet.

May will be a bit less crowded and the weather is usually good. You might get a bit of rain but it’s never an all day event.

I also recommend Julie Dawn Fox for great information on smaller towns.

Thanks to all who posted. please keep the comments coming. I’ll reconsider the car rental for part of the trip. Unfortunately I’m not skilled at a manual transmission and either need to cross fingers for an automatic, stick with trains, or learn something new..
Haven’t heard of the silver coast thanks for the link.

If I decide on a few days in Madeira, I assume a car is crucial unless there are buses, correct?