I really like Thomas Swick's definition of travel:
Today I think of travel as anything that extends one's realm of experience or expands one's lexicon of acquired convictions and occurs beyond the backyard (this distinguishing it from reading).
From "Charmed Lives: Reflections of a Travel Editor on Abroad and Home"
The Oxford American. March/April 2001, p. 58.

Swick relays in his article a story about "traveling" to a friend's house, where the style of parenting was 180 degrees from anything he knew. In his mind, this was traveling to a foreign place as much as going to Paris.