I am looking for a place to live pretty much anywhere in Europe as I work remotely and live alone my options are wide open. Based on some past experiences I need city life, I can't do rural, didn't work for me. I also lived for 15 years in Vancouver right on the English Bay and two in Malta also right on the seashore and so now I don't think I want to live without water views. Based on my requirements for water, city size, weather and affordability from the entire EU the Northern coast of Spain like San Sebastian, Bilbao, Santander, Gijón and the close by Atlantic coast: A Coruna and Porto in Portugal are my primary candidates. I do not speak Spanish though. Do you think it could work?

You can live anywhere without speaking the language but it is a lot, lot harder than doing so. For official stuff you can hire a translator, you can walk around all confused how things operate and how to manage day to day life. You can shop anywhere that doesn't require you to say anything or take note of any signs, you can speak to nobody other than hello and thank you. You can play the game of ordering from a menu by pointing at the item and putting one finger up then wondering what on earth you've just ordered. Nice surprise anyway.
You can speak to no one, understand no one and understand nothing written but you can delight in the feeling of getting a few words understood though with strange looks when you mix up things like molest and molestar and even have no idea if it is Asturian you are reading and hearing.
So yes you can, it just depends how difficult you want your life to be for quite some time until you get to grips with it.

Many people start out speaking no Spanish whatsoever some learn a little some learn non some become fluent. Im sure you would pick up some spanish. As has been said anything is doable some things may be a little daunting and you will need help but Im sure you would get by ok.

Las Palmas de Gran Canaria. Part of Spain, part of the EU (albeit not part of the EU VAT scheme). I don't think you can beat the weather anywhere else in the EU; it's literally perfect all-year-round.

Register as resident and you even get a 75% rebate off all flights to anywhere in Spain. Cheap way to get away for a weekend in Madrid or Barcelona...

Language Apps are improving all the time and can help at lot. Apps such as Reverso, Google Translate and ChatGpt can work wonders.

I lived in Logroño years ago. It is very difficult to live on your own without the language as these places are not anything like as dependent on tourism as in the south. Of course, nothing will happen to you but you can't go around just expecting people to speak English nor will you be able to communicate anything meaningful with little or no Spanish. If you aren't working with Spanish people you will also have little opportunity to practice. I imagine there are small expat groups around which would help but not sure it would suffice. I think it really comes down to your personality. If you are happy on your own you might not mind but it will take a few years of constant studying to reach a point where you are able to feel comfortable with day to day things in Spanish and by then the shine will have worn off a bit - so it could be tough.
I was in my late 30s when I was in Logroño and only managed a couple of months as I just felt too stressed doing anything ( which back then meant having to do everything in person as no internet etc!)

Hello chx and welcome. I live in Santander and have been to all of the places you mention. Like you I prefer cities and coundn't live in the outside - even suburbs are too odd for me.

Spain is unlike other European countries in that people generally don't speak English. In the north of Spain this extends to the people who work in the places you need to go to to get your documents. So as said if you decide to move here it's best to learn Spanish as soon as possible. One tip is to find intercambio conversation partners who in my experience will help you get settled and show you around their city.

If you haven't already done so have a look at idealista.com to compare property and rental prices. Roughly speaking prices drop as you go east to west.
Where I live, Santander, is unfriendly no matter your level of Spanish so unless you're really a hermit I can't recommend it. Elsewhere people are welcoming and with intermediate Spanish you'll be able to chat to people and make friends.

You don't say how long you plan on staying. Two things I've been mulling over are climate change and AI. The former could swallow up zones too close to the beach and make the north west unbearably stormy, or at least put up your insurance costs. The latter could spell the end of cities populated by office workers, and perhaps Bilbao will suffer. So it's best to choose somewhere people will want to live for its beauty, rather than function. For these two reasons Santander is a good choice as the centre is away from the coast and is very pleasant.

How would you describe "unfriendly" when it comes to people in Santander? Is it the general attitude towards foreigners in general, even if they're from the EU/UK and not another continent?

I'd say there's 2 things going on. First, that Cantabria is a region known in Spain as being 'closed', as they say, which I suppose means that they don't open up to new people like Spaniards do elsewhere. (I lived in various places in the UK and noticed that farming areas are like that.)
Second is the ferry which brings many British tourists, but only for a short time. Not many here speak English so I think they've got used to hearing a British accent and assuming they won't be able to communicate with them and that they won't be a repeat customer.

The anti-tourism movement isn't as strong as in e.g. Barcelona. It's recognised that tourism plays a major part in the local economy and the local papers often report the hotel occupation figures.

And while of course there are Vox voters here there doen't seem to be a lot of overt racism - I'm white so maybe I'm not seeing the obvious.

However I was perhaps a bit unfair due to a bad experience that morning. Once they know that you live here they'll talk to you, and if you're with a Spaniard they're more friendly.

We stayed in Santander (3 weeks) and also San Sebastián (one of my favourite cities in the world) we only speak a tiny amount of Spanish and certainly no basque and we found both cities to be exceptionally friendly especially San Sebastián I dare say more so than the Southern “costas” maybe because we were friendly tourists.

Gijon or anywhere in that general vicinity is not somewhere I would want to live if I was on my own with limited Spanish. I think there are more suitable cities to choose from, perhaps somewhere further south. Porto is definitely worth considering because English is widely spoken there and it is accepted that most people have English as their second language and people are not reluctant to speak it. Ditto other places in Portugal but Spain less so in my experience.

I'm sure there are plenty of English speakers in Santander, San Sebastian, or Bilbao, it's just a case of finding them...