I know guys most of you fly across the Atlantic to see this and other countries and, understandably, would like to "pack" as much as possible in this trip, but it's a shame because you end up not really seeing much of anything. I guess you'll agree that 'seeing' is not just ticking a box, but also soaking a bit of the ambiance, the people, the nooks and crannies, the little shops, the secluded taverns, the stories, the traditions and celebrations... in short: the whole atmosphere of the place you're visiting. And that's especially true when there's so much to see and do in this part of the world: culture, history, folk, ancestral traditions, art, architecture, gastronomy... you name it and there's something for you somewhere.
I'm pointing this out, because when I see (for example) Barcelona 3 days, Madrid 2 days, day trip to Cordoba... my heart bleeds ;) as it's materially impossible that you really get any sort of idea of these places at all in such short hops -moreover when you spend half of the trip travelling. It's not my aim of course to tell others how they should plan their trips, everybody's got his own 'style' and his own preferences and most importantly expectations too (some prefer quantity, others prefer quality), but since planning is really an art no matter how often one has traveled, I feel it's important to bring to attention that aiming too high might result in poorer experiences when visiting Europe for the reasons I mentioned earlier. If you've got 10 days, it's best to aim for a couple of 'base camps' -likely to be two major cities, best in different regions, which will occupy you quite a few of those days- and then do escapades to many little gems that are a stone throw away from them and that you can easily reach by local train or buses. Anything else leave for your next trip. This way you'll be able to really enjoy the many different communities there are this side of the pond.
For reflection: Europe is over 50 countries, but there are nearly 350 distinct regions or communities within the continent that go beyond defined 'country borders': http://www.aer.eu/fileadmin/user_upload/PressComm/Publications/Tabula/Tabula2013/TabulaJPEG.jpg This makes it a very rich tapestry of different ways of doing and seeing things, languages, traditions, history too... In a manner of speaking, some trips to 'a country' end up turning into an adventure as you discover that what you though it'd be "one" turns to be "many", in fact as if you had visited different countries one could say! A good example is Spain, where there are so many differences between regions, even the feeling of their people... would it surprise you to discover that lots of people in different regions don't feel Spanish at all?. And this happens in Spain, but also in France or in Belgium among other countries.
This is just a though from someone living here and that's passionate about the many things one can see and do around these shores.