Specifically... traveling as an adult.
I remember the first time I got on a plane alone. I was traveling to DC for a journalism convention in high school. It was the epitome of independence - I had to change planes, make sure I left myself enough time to eat, navigate a new airport and find my cousin at the end.
But far better was my first big trip, including plane travel, with friends. Age 20, Spring Break in Hawaii. It was do-what-we-want week, and I felt I'd arrived as an adult.
Even better... traveling alone now. Every single time I go into an airport alone, I think, wow. No one knows where I am, no one knows who I am observing in the airport, no one would yet know if I switched flights and went to Bhutan. It's the very definition of a thrill.
And on that note... I'm off to Bend, Oregon! (There, now you all know and don't have to worry.) For a wonderful weekend away with friends and John, and I hope we experience a little of the thrill of doing your own thing, a little of the joyous parts (for a change) of being an adult.