The title references the Dr. Seuss classic, Oh, the Places You'll Go!…aka the gift high school and college graduates have received since the beginning of time (or at least since 1990).
It's a coming-of-age story about the ups and downs of life—and it's also the last book that Dr. Seuss published before he died. It's a happy, hopeful book, but it has some sadness, too.
When Finch and Violet break into a bookstore, Oh, the Places You'll Go! is one of the books they read together:
We alternative stanzas, first Finch, then me, Finch, then me.
Today is your day.
You're off to Great Places!
You're off and away!
At some point, Finch gets to his feet and starts acting it out. […] His voice turns serious as he recites lines about dark places and useless places and waiting places, where people don't do anything but wait. Then his voice turns light again and he is singing the words.
You'll find the bright places
where the Boom Bands are playing.
He pulls me to my feet.
With banner flip-flapping,
once more you'll ride high!
Ready for anything under the sky. (20.31-20.37)
All the Bright Places, then, refers to those golden, perfect moments in a person's life—the ones that make you happy. Oh, and it also refers to the tourist attractions (the many wonders of the state of Indiana) that Violet and Finch are visiting for their school project.
The thing to remember about bright places, though, is that they can only exist in contrast to dark places. That's true for everyone—hey, we all have highs and lows—but it's especially true for Finch, who has bipolar disorder.