Earth
Earth is the third planet from the Sun, located in the Solar System. It is the only astronomical object known to host life (bacteria, flora, fungi, animals, including human hitchhikers). Contrary to popular myths hitchhiking is (still) pretty doable in most countries on Earth. You will find that local hitchhikers and those who pick them up are mostly harmless*.
Earth is definitely my favorite planet to hitchhike on. Plenty of oxygen and the temperature is just right! It also has an abundance of humans with vehicles. --Keith