Yup, we all went off to holland. We flew TAP Air Portugal and there was no particular problem with me travelling. As long as you keep your weight under about 7 kilos, you are allowed to travel in the cabin of the aircraft. More than that, down below you must go with the cargo. I weighed about 9 kilos at the time, but I looked so cute in my travel bag that the girl at the check-in counter couldn't resist letting me go in the cabin. You have to pay extra ( how much it is depends on the destination ) and your owner loses the right to carry hand baggage because you become the hand baggage. As for arriving in Holland, we had no problems as I was allowed right through without any checks but you must take the little book that proves all your vaccines. The same happened when we arrived back in Portugal. Certain countries, however, England and the Scandinavian countries come to mind, have a problem with pets so it's best to get your owner to check with a consulate or embassy before you go just to ensure you don't end up in doggie prison for 6 months.
As for the actual travelling, I loved it! My owner took little doggie treats which he gave me as the plane went up and down because of the pressure in my ears. The doggie treats made me swallow and so kept my ears clear, just like in humans! I think the TAP flight attendants liked to have me on board more than I liked being on board because they kept bringing me water in little bowls from business class!
Being Portugal, you might hear the odd subdued "Dogs don't belong in the cabin" type comments, but I also heard one woman saying "O caozinho estive mais bem comportado do que aqueles dois por tras de nos!!" You'll love the flying!!!