We have cruised with RCCL a number of times in the Caribbean, so we knew what to expect on Voyager, and found the experience to be very consistent. I have traveled in Europe before, but this was our first cruise there, and to these particular countries.
Before Boarding A couple of simple things made for a great trip... we packed two collapsible umbrellas, a small set of binoculars, and took along two ATM and credit cards that worked in Europe. (Mine have the Cirrus and Plus emblems on the back, I'm sure there are others that work, too.) We ordered only a small amount of Euros before we left, and used ATMs in port cities for the rest. That is likely the best exchange rate, but check the fees on your cards. Our local credit union ATM card carries a 1% charge, compared to the US Bank ATM card, which carries a 3% charge. Both worked in Europe. Same with the credit cards. Make sure you notify your card carriers that you are traveling.
Air We arranged our air through RCCL this time, and the connections worked well- Iberia on the way to Barcelona, and Air France on the way back. I would not choose Iberia again, however, as the headrests do not have video units in coach, which is a great comfort on an 8 hour flight. The transfer in Madrid was a little confusing, too, as the connecting flight had the same number as our original flight, but the gate did not use that flight number- it had no less than 4 other numbers. That made finding our luggage a little challenging. Watch your wallet in the Barcelona airport- into your front pocket if your trousers are snug, or into your carry-on if not. One of our CruiseCritic.com buddies lost his wallet out of his front pocket to a pickpocket.