Travels through time and space:
A Wrinkle in Time by Madeleine L'Engle: Do I really need to explain this one?
Travel between parallel worlds:
The Lives of Christopher Chant by Diana Wynne Jones: Oh I love Christopher so much and his character is forged a lot during the journeys he takes in this book.
Travel of the teen tourist variety:
Usually I like these books better in theory than reality, but Meant to Be by Lauren Morill and Just One Day by Gayle Forman are exceptions. I loved them both in theory and in reality.
Traveling on a jet plan:
And because we all know how much I love fantasy, here are my traveling on a quest picks: