The fundamental problem here is that "all-inclusive destinations" are a creation of the 21st century tourism industry. As such they are yield-managed to the Nth degree, and part of that is the cost of the land on which they are built. Which means that you will not find many in the Spanish equivalent of Shoreditch or Didsbury.
This also makes sense given that the whole point of an AI destination is that you spend a minimal amount of time and (especially) money outside the hotel. I don't think you can't have it both ways — all you can eat and drink, but somehow also being part of the local culture. In some seaside towns the AI hotels have almost destroyed the local bars and restaurants (Calas de Mallorca is a particularly depressing example).
So if you choose an AI destination, no two ways about it, you are going to mostly be near other AI destinations, in a resort town. The majority of the people sleeping within a 500 metre radius of your room will be other Brits and northern Europeans on their holidays, because you are too. There will probably not be a quaint cafe nearby where people idly strum flamenco guitars and drink vermut, because the local people are all working in your hotel.
Now, that's all horribly negative of me, so let me try to make amends and suggest that you look for somewhere that is a reasonable bus ride from a "real Spanish city". To that end I would go on Booking dot com and look (using the map-based search, which is pretty good) at places that are within 20km or so of Santa Cruz de Tenerife, Alicante, or Palma. I know Majorca best, so I would suggest Palma Nova or (don't laugh) Magaluf, where there are some quite nice AI places in the southern part of the town. (Or Playa de Palma, but try to stay west of the midpoint to avoid the 10-litre-a-day German party crowd.)