Had a school trip to DC at age 12, but after that my first real trip without my parents was when I was 19, I went to Montreal with my younger sister (17 at the time). Took the train up from NYC, and stayed at the Montreal YWCA. I carried a letter from my parents stating my sister was OK to travel with me and not running away, just in case. DIdn't do anything that could get me in trouble but enjoyed the sightseeing and being in a different country (my first time out of the US). My first air trip was to London when I was 22, among seeing the sights, I randomly stumbled upon seeing Prince Charles and Princess Diana leave the hospital with newborn Prince Harry!