if you love strolling around a beautiful city either would do and for most of your other requisites as well - these are two of the most delightful and vibrant cities in Europe IME - BUT in late March or early April I'd take Barcelona hands down simply because of the much better weather down south - not that Barcelona will be really hot or anything but in Amsterdam be prepared for windy wet weather at that time of year IME - not so fun for strolling around.

I think what you are asking is a matter of taste.

Amazing art and museum and architecture: Barcelona - Picasso, Miro, Gaudi...; Amsterdam - Rembrandt, Van Gogh, Vermeer...

Good restaurants: Barcelona has OMG Tapas bars, Amsterdam has Indonesian restaurants if you are not into Dutch food.

If you can visit Amsterdam closer to middle April, you might hit the outdoor tulip season at the Kukenhof Gardens http://www.keukenhof.nl/. They are open 3/21 - 5/20 next year.

Barcelona is my new favorite city especially after numerous trips to Spain and particularly avoiding going there. But, BUT, there is nothing quite like all those canals, those houseboats and alllllll those bikes and windmills and tulips! Very simplistically, Barcelona,although having interesting characteristics is really nothing compared to the uniqueness of Amsterdam. (have been to both cities twice).

To me a non-direct flight would be a deal breaker since the whole trip is only 5 days. Granted Barcelona will be warmer - and a top hotel probably less expensive than in Amsterdam.

But March isn;t the depths of winter (and I don't mind chilly weather - prefer it to hear) and I find more to see and do in Amsterdam.

Barcelona is bigger ...fantastic food, interesting architecture, great shopping. And the Mediterranean !
In March and April we had lunch in outdoor restaurants - the weather was so nice.
Amsterdam is charming but in the rainy weather I find it
a bit gloomy. On a sunny day, it is splendid.
I have visited both cities five -six times.
Barcelona is always my first choice.

I've been to both in March, for a week each. You can't go wrong with these choices. Great museums, charming cafes and restaurants, interesting architecture, excellent accommodations, plenty of easy day trips (Den Haag and Harlem; Montserrat), beer in Amsterdam, wine in Spain. We had some snow in Amsterdam but that made it more beautiful, if crisper; Barcelona was warmer but still quite cool. Flip a coin and go with the winner. You'll love both of them!

Thank you, everyone, for your thoughtful responses! If we pushed our trip back to the 2nd week of May, could we still catch the tulip season? Both cities sound so amazing!

If you are not interested in night life, be aware that most of Spain lives to a much later clock than in Amsterdam. If you are happy with tapas for dinner, you can reasonably expect to be asleep by 11pm each night in Spain, but otherwise dinner doesn't really start untll 9pm

There is good beer in both places, but I don't think is much in the way of wine in Amsterdam. Food in general is far less exciting or interesting in the Netherlands than it is in Spain.

There is a new luxury design hotel in Amsterdam (Andaz) if you can take the price tag, but overall Barcelona has consistently set itself out to be a trendsetter in architecture.

People argue about this, but quite a few travelers find the extra level of precaution needed in Barcelona against pickpockets and other thieves and scamsters to be an un-relaxing nuisance and impediment to enjoying their vacation even if they don't get robbed.

Finally, not everybody likes both cities. I wouldn't just flip a coin. I've been to both citeis and I know where I'd rather be, and where I wished I hadn't bothered to go in the first place, and I enjoy travel as much as anybody else here. So figuring out which one most appeals to you and your husband for such a brief vacation is worth the investment in thought.

good wine in both countries, just not much made in the Netherlands. Not much good beer made in Holland but since Belgium is next door (probably in the top three beer countries in the world) who cares as much is sold through out Holland. Dutch International food has come on leaps and bounds in the past 20 years so I would think you can eat as well here as in Barcelona.

No direct flight would make me stay in Amsterdam