We did it! First cruise in 2010 we flew from Portland, OR and landed in Barcelona around 9:00 am. We too k a taxi directly to the airport and then after our cruise we took a taxi right back to the airport to fly home at noon.
Now, having said that and eventhough everything went smooth for us we became very aware that it could have been a different story. We also realized how amazing Barcelona looked. We now always fly in at least a day early, just in case, as well as to help us adjust to any time change. If push came to shove and we had no other option, we would fly in day of, but would make sure we had trip insurance.
The good thing with Europe is that it is very port intensive and not too far in case you had to join the cruise at a different port. Have a great cruise!