I would be some kind of bird which can fly long distances, so that I could fly around the world and take a look at everything I have ever wanted to see... well as much as I could fit into a week anyway :-)
Either a seal, I'd enjoy that agility and the whole speed sensation or some sort of bird that glides alot so I could just chill out and look at the view.
Good question! I'd be a little dog as long as I was with nice people who spoiled me and let me have the best spot on the sofa and took me everywhere with them. Oh and fed me all the best doggy delicacies but also took me walking lots!