We've just returned from Madrid, and thanks to Chowhounders we ate some great food, but we also had some misses. So I thought I'd share our thoughts. (We also visited Seville on the same trip and I've written a separate report on our experience there - see http://chowhound.chow.com/topics/785952)
In Madrid, we were staying in the Recoletos area, close to the NW corner of the Retiro park, and in general we found that the tourists disappeared as we moved east from there.
Our two favourite bars for tapas were:
BIOTZA, Calle Claudio Coello, 27 (in the Recoletos/Salamanca area). It's worth pushing your way through the (overwhelmingly local) crowd to get some tapas at this busy place. The food was some of the best we had on our trip. If I had a local bar that served calamari as good as that at Biotza, I'd be there every night! But our other food there was lovely too, and good value.
ARZABAL, Calle Doctor Castelo 2 (facing the NE corner of the Retiro). We loved Arzabal - the staff were incredibly friendly; the food was lovely; the bar had a great vibe and we seemed to be surrounded by locals, not tourists. Salmorejo (tomato soup) and marinated sardines were particularly good, and there was a fantastic choice of wine. So good, we returned another night - to be warmly welcomed by the staff.
Another evening, we had some tapas in La Colonia de Goya ( Jorge Juan 34, also in Salamanca) but we didn't stay long - the only white wine they had was sweet, and the tapas we ordered were all extremely ordinary in taste and presentation. And yet it was relatively expensive too. Of course,the beauty of tapas is that you can just move on when the food disappoints.
Oh, that we had been able to do that when we went to LA TRAINERA! This was the biggest disappointment of our Madrid trip. We were meeting friends and I had booked this famous fish restaurant in advance of our trip. But my advice to people would be to avoid this restaurant, or least be prepared that:
1. If you are a tourist, you will be directed past the buzzy front room and bar to one of the back rooms where they seem to corral all the foreigners, where there was no atmosphere (we asked to move to a different room, but of course they couldn't accommodate that and after that the service was decidedly icy).
2. They will recommend items that are not priced on the menu, that are astonishingly expensive (our waiter suggested the turbot, and when one of our party seemed interested in it, the handsome fish was brought to him with a flourish - when we asked how much that would be, he went away to check, and came back with a piece of paper on which was scribbled Euros 54.60!! That was for one piece of fish alone!).
3. Your fish will come on its own, with no sides of any kind - no carbs nor veg. My grilled sole (Euros 28.50) was lovely but I would have appreciated something with it, yet the menu contained no side dish options nor was anything offered.
Overall, the whole experience was incredibly irritating, and we won't be returning to La Trainera.
However, in general we loved Madrid. One final, non-food tip - we took a 3 hour cycle tour of the city with Bravo Bikes, and it was an absolutely fantastic way to see the city. In addition to telling us about the places we passed, our guide also pointed out his favourite bars and cafes as we moved around town. We highly recommend it!