chanad

Which one would you suggest, and why? Thanks!

Intrepid1

Given the lack of information on your part and having been to all three I would suggest you try to visit all three.

chanad

whoops! sorry. I would love to see both but I will be in Spain for only four days in December, on a stopover. I can either stop in Madrid or Barcelona.

buongiorno

I've spent time in all three and my favorite is Barcelona. We stayed at a great little hotel on Las Ramblas which is very vibrant. There's also an unbelievable open air food market there and it's very close to transportation for activities. They have these hop on hop off busses that take you all over the city for one price and you can see all the interesting Gaudi architecture along with other sites. We had a great time there.

Gardyloo

Warmer in December, less smog, more compact - BCN.