What guidebook?

Get ebooks at the Seattle Public Library

Rick has two "Snapshot" guides to those regions, each of which is a section excerpted from the latest editions of his larger country guides: https://store.ricksteves.com/shop/guidebooks/spain.

There is no best. Go to a bookstore and look at some different ones to see which you like. Each is formatted differently and not all cover the same places. Some guides are Rick Steves, Fodor’s, Frommers, DK eyewitness travel guides, Insight Guides, and Lonely Planet. Check to see which one has the most information on the places you want to see. Of course, you can also do internet research. There are many websites on those cities. Researching a trip is almost as fun as going on the trip.

Edited. Here’s a link to the Tourist Office of Spain: https://www.spain.info/en_US/

In the meantime, you can find the basics on all 3 cities by going to Explore Europe, selecting the countries and then the cities.

These are two countries (Spain and Portugal) which receive millions of tourists every year so their TI offices and the major cities' tourism websites are quite good as their tourism industry is very developed. Spain alone receives the same number of international tourists than the US, yet its territory is 20 times smaller in size. Regardless of the guidebook you end up getting, a look at the websites is a must since you'll get more accurate and updated information and also more "local" -if you catch my drift.

Buy Rick's guidebooks and tear out the needed pages.

And if you like, Rick sells $1.00 folders to bind your torn-out pages into. When I went on a Mediterranean cruise I visited six cities and swapped in the relevant pages each night. It felt really wrong to tear up a book, though.

I typically use library books. Favorites are RS, Lonely Planet and Eyewitness travel. I typically copy pages and put in ziploc bags by city. I throw away pages as I go. Sometimes I can't find info on certain cities and have had surprisingly good luck with emailing TIs in various cities and have received mailings with extensive info.