I've had a Gameboy since the original came out in 1989. Over the years, I've upgraded to better hardware, but I still retain an original DMG Gameboy, a Gameboy Color, a Gameboy Advance, and a Gameboy Advance SP, and all of my original carts. Many many car trips and hotel stays were spent with my Gameboy games in hand.
In all these years, I still find myself bringing my Gameboy along in some incarnation when I travel. Usually either my Gameboy Color or Advance SP hardware, loaded with an GB Everdrive (for simplicity of not having to swap carts). Other times, I bring my 3DS and play my GB Virtual Console games on it.
My point being that the Gameboy brought so many great portable games into the world, that despite the current world of smartphone and app-based gaming, I still prefer to chill out to the Gameboy's library of greatness.
Give me Gameboy Tetris over Candy Crush any day!
Surely, I can't be alone in this behavior. Do any of you still play GB games (in some form or the other) when you travel?