Spain/Portugal/Gibraltar - last minute trip to Madrid and Barcelona---any tips?

My husband and I are leaving next Sunday (I booked the flights yesterday) for a quick trip to Spain, 3 nights each in Madrid and Barcelona. There are some tapas walking tours in Madrid that sound good to me. This was the first one I found:

http://www.viator.com/tours/Madrid/Madrid-Tapas-Night-Walking-Tour/d566-2294ADVTAPAS

(Note in the reviews that the guide generally seems to be Irish.)

This one is actually run by a native, and I think it sounds a bit better:

http://www.walksofspain.com/tour-details/

Does anyone have any experience with walking tours in either Madrid or Barcelona?

I was just in Barcelona in July and did the RunnerBean Gaudi free walking tour:

http://www.runnerbeantours.com/gaudi-free-walking-tour.php

The tour was excellent! So much better than I expected for a free tour. The tour lasted 2 1/2 hours and covered all of Gaudi's major buildings in Barcelona. If I would have had more time, I would have taken advantage of the Old City walking tour they also offer.

While the tour was free, we did tip our guide 20 euros at the end. And she was totally worth it!

I engaged in a week of cyber-silence (it was fun!) while we were in Spain, so this reply came too late to help. (I guess cyber silence does have its drawbacks....)

Anyway, we did not end up doing a tapas tour (though we ate plenty of tapas!), but did do a Modernism walking tour in Barcelona, given by the tourist bureau. It was excellent, well worth the 13 euros/person. A great feature of the tours run by the tourist bureau is a little radio and headset for every participant, so you can be quite a distance from the guide (who is talking into the transmitter) and still hear everything. Commentary could (and did) continue while walking down the street, for example.