Madrid and Barcelona

My first though is to try and get another day or two. These are both great cities, and they're worthy of all the time you can spend there.

We were surprised how economical travel to Spain was--in comparison with other popular European countries. We went from Madrid to Granada and then flew over to Barcelona.

And we will return.

It depends on if you are a big Gaudi or beach fan. my husband preferred Barcelona cause he loves the water, even just walking along the coast or sitting and watching the boats go by. We stayed within walking distance to the water. We were there in early October and friends of ours went to the beach. Not big Gaudi fans so we skipped the park. We spent 3 nights in Barcelona and 6 in Madrid. I preferred Madrid cause I am a city girl. We were busy everyday.

Fly open jaw where you arrive in Madrid and depart from Barcelona, you may pay a bit more but time is your most valuable commodity.
Madrid offers a small Old Town set among the third largest city of Europe. We enjoyed a three day visit and did not take any day trips (Toledo is a common day trip). If you love museums then do your research and plan accordingly.

Take the AVE to Barcelona allowing some time to explore the Atocha train station prior to departure.

Barcelona offers a huge diverse menu of opportunities so we advocate for five days to explore the city.

If you split evenly, the first city may be significantly shortchanged since your arrival day is a partial one and you may be jetlagged or sleep-deprived for at least that first day. There are frequent, very fast trains between the two cities, so if you are an early riser, you can easily get to the second city before noon, raring to go, on the day you shift.

I think it matters a lot whether you are nuts about modernista architecture (tilt toward Barcelona) or art and nightlife (maybe tilt toward Madrid). I say "maybe" because I just prefer Barcelona in general, despite my love of art museums (though Barcelona has some good ones itself).

I agree that a few extra days would be very handy here. Both cities have great neighborhoods for wandering, and both have worthwhile day trips (advantage to Madrid, I would say, though I adore Girona).

I have to agree with acraven with her take in comparing both of these unique cities. I will reiterate my take from a previous posting. At the time our stay was limited. For us 4 nights in each city worked. We had just completed a 2.5 week tour of Portugal. Enjoy your planning! Edited to add:
https://community.ricksteves.com/travel-forum/spain/barcelona-7d97e3c6-63cd-48ce-a495-165ab637b5dd

Both are equally great. We spent 5 nights at each last month and could have easily enjoyed another 5 nights at both. I think you would be short-changing yourself if you were to split the days 5:3 either way. If you were to ask me which one I would pick if you had an extra odd number night (i.e 9 nights), I would still flip flop between the two; pick one one day and pick the other the other day. Also compare airfare flying open jaw in reverse order; sometimes one way is cheaper than the other.

One good option is 4 nights in each city. However, as acraven points out, your first destination will be shortchanged a bit because you do need to get over jetlag and will probably be wandering around your first city bleary eyed and tired. So you could spend 5 nights in your first city and 3 nights in your last city.

Another consideration, however, is your interests. If you haven't already done so, buy a couple good guidebooks and read up on what each city offers. Lonely Planet, Fodors, Rick Steves and Michelin Green Guides are books I frequently use.

Regarding your interests, if you love the Gaudi architecture, then perhaps spend 5 nights in Barcelona to see the many awesome and unique Gaudi buildings, such as La Sagrada Familia, Casa Batllo, Casa Mila, Parc Guell, etc and other impressive buildings such as the Palau de la Musica and Hospital de Sant Pau. Visit Citadel Park and La Cascada. The Barcelona Cathedral and Boqueria Market. Wander the very different neighborhoods, such as Eixample, Gothic Quarter and Gracia.

But if you are not a huge Gaudi fan, and you are an art fan, then it might make sense to spend more time in Madrid. Barcelona does have art museums, but I think Madrid's art museums are outstanding. There is the Prado, Reina Sofia, and Thyssen Museum, and many smaller art museums. There is the Royal Palace, Temple Debod, the lovely Retiro Park, and wonderful neighborhoods.

So, either split your stay in half equally, or give an extra night to the city you think holds more interest to you. Either way, you can't go wrong.

Of course, as others have suggested, if you can add an extra night or two to your itinerary, that would be even better.

Everyone is different. I like Madrid as much as I like Barcelona. My husband and friends we were traveling with prefer Barcelona. It really depends on your interests.

And if this helps at all, we spent 5 or 6 nights in Barcelona and didn't see everything. We spent 4 nights in Madrid (no daytrips) and didn't see everything.

Whichever way you split it up you will wish for more time! No bad choices

While in Madrid, take day trips to Toledo and Segovia.

Four days in each will be minimal. Try to add a few more days. I prefer the the more Spanish Madrid over the Catalan Barcelona.

Toledo and Segovia are nice day trips from Madird, but it doesn't sound like you'd have time for them. 3 full days would be an absolute minimum to give the city itself an overview—4 probably better. Only with more time is there really time to consider day trips.