Spain itinerary

I agree with above but I'd say go north or south, rather than both. Im May you can probably choose either weather-wise. South, I'd suggest Cordoba for up to a day, Granada for at least two days, Seville for at least two days. Add Jerez plus Ronda or Arcos. Consider adding Cadiz, Costa de la Luz, Tarifa (with or without a ferry to Tangier, we chose without) and Gibraltar. Maybe also the Dolmen in Antequera, depending on how you're getting around. North, Madrid and Barcelona. I'd do a couple days in Madrid (my must-sees are Prado and Temple Debod) more in Barcelona, at least three full days. There are lots of choices in Northern Spain. We did a loop beginning in Barcelona, Montserrat, Zaragosa, Olite (great little castle here), Pamplona, San Sebastian, Vitoria, Burgos, Coca, Pinafiel, and La Roca castles, Salamanca, Avila, Segovia, Toledo (picked up Madrid last after looping south). You can also choose to go toward Bilbao and see some of the coast to Santiago de Compostela.

I'm not sure what a side trip is, but if it is a day trip I do not think it would be satisfying to visit Granada while based in Sevilla. I'd recommend two nights (allowing for a full day there), though I concede you could have a worthwhile visit with only one night, if you are very nimble. Cordoba can be seen as a day trip enroute from Madrid to Seville (or vice versa): leave early, stop in Cordoba, arrive on the late side. Finally, doubling back to Madrid wastes time. Can you avoid this?

Comments and presuming when you say 'side trips' you know your way transport wise. I have no idea what Rick Steves recommends or the info. he provides. Sevilla to Tangier and return is a big day for a city which, to many, only gives an industrial port city which could be almost anywhere on the Med. and very little of Morocco. Seville to Granada and return is three hours each way by whatever transport, plus time to make your way in the city to (presume) the Alhambra and some hours of 'dead' time. Consider staying in Granada and flying Granada to Barcelona. And, yes, can you not fly home from Barcelona and spend time in Madrid initially? For me, but I am not you and have no idea of your travel style and how well you will plan your site seeing or what interests, you are trying to do too much. Not devoting enough time to M. B. and S. and counting travel hours towards the time expended in those cities.

If you only have 13 days and that includes your days flying to and from the US, it's hard to do justice to Madrid and surrounds, Barcelona and surrounds, and Andalucia. Pick two of the three, and you can actually have a trip instead of an endurance test. Yes, if you want to do something resembling your posted itinerary, fly into Seville and out of Madrid. It may not cost more, and even if it does, you have to account for the time and money you spend on the train from Madrid to Seville. I agree with Neil and Adam; you are planning to see places as "side trips" from Seville that are too far for this. The only place on your list close enough to Seville to see this way is Cordoba. And most feel that a day trip to Toledo is just frustrating, but spending a night is very worthwhile (it gets very crowded during the day and is supposed to be much more pleasant when all the daytrippers leave). If there are any must sees in you side trips (for example, if Toledo is a must-see), allow more time in your base cities. Trying to see Madrid and Toledo in 2-3 days will just leave you exhausted and frustrated.

Just returned from Rick Steve's tour to SPain and Tangiers. Here is what I would do: Start Barcelona (2, then Madrid / Toledo (3 days) - Then hit Sevilla. (2 days) Then to Granada (2) Cordoba as a stop on way to airport and end in Malaga and fly home from Malaga. You can do it all by train. Hotel Barcelo in Malaga is right at the train station and you can get great and relatively cheap flights out of Malaga - just fly open jaw to Barcelona and then return from Malaga. Skip Tangiers.