I am flying in and out of Madrid, but will be spending the first portion of my trip in Barcelona. Since I will already be at the airport, does it make sense for me to fly from Madrid to Barcelona rather than taking the train? It seems faster and less expensive, but I wonder if I am missing something. I do plan to take the train to Madrid for the second half of my trip.

If I do fly, how much time should I expect that it will take me to get through customs and retrieve my bag? My flight from the U.S. gets in at 7:15 a.m. on a Friday...

There are memorable sights along the path of the train from Madrid to Barcelona.

Yikes I omitted the key word

There are FEW memorable sights on the path of the train from Madrid to Barcelona.

I would advise flying. There are many flights by several airlines in that route, and as you said yourself , you will already be at the airport. To me it would be an additional hassle to get to Atocha to get the train.

agree with PPs