I would say that I've traveled a decent amount for my age. Between shuttling back and forth across the US due to college and annual trips to China (plus random trips within the US and abroad), I've had enough experience to determine what is the most ideal tech to bring on a trip to stave off boredom (well for me personally).
Back when I was just a scrub (I mean a kid), the only form of entertainment that I had on flights was my old trusty PSP and GameBoy Advance. Those things had to survive 13 hour flights to China. Now that I'm an adult (oh god I'm an adult now huh), I have more freedom to decide/purchase things for my own entertainment. Over the past couple of years, I've more or less cemented my "must-need" technology for long trips.
Below is a list and a brief description:
iPhone - I hope everyone brings a smartphone on their travels. This tool is extremely necessary especially if I'm in a foreign country and I must use GPS to figure out where to go. This saved my ass many times over in my trip to Japan. Sim cards are so easy to acquire in foreign countries and they are super affordable.
MacBook Pro - Gotta have a laptop. When traveling to a new destination, shit could happen and I might need to get on a computer ASAP to change itineraries. Plus it's nice to have when I'm at the hotel/hostel/AirBnB and can have my social media/internet fix at night. It's also a great tool to research things to do when I'm on vacation (much better than looking at a tiny phone screen).
Kindle PaperWhite - This was a recent purchase of mine, but boy has this changed traveling for me. I haven't read a lot for fun in college, but this Kindle has really made me pick up reading again. I have a ton of books recommended to me by friends and books that I've always wanted to read loaded up. I've been reading a lot on planes and it makes the time go by so quickly.
Playstation Vita - This was... more of an impulse purchase. I used to own the original PSP and wanted to purchase the newest model so I could play all the old games that I used to play. I have a PS Plus membership, so I get free games every month. So far, I haven't been utilizing it to the fullest potential as lately I would rather read than play games (oh shit I really am getting old).
Earphones - This is a must. Personally, I cannot stand the sound of other people talking and the sound of vehicles/planes. By drowning out those sounds, I can keep sane and calm. I used to have really crappy $10 - $20 earphones that I would break or lose in the span of a few months. I decided to splurge for expensive ones as I can easily spend hours a day listening to music. Boy do expensive ones sound so much better than the cheaper ones.
Camera - Does this count? Actually whatever this is my blog, I'll make it count. Taking photos is relaxing and fun for me. Traveling to a new place and see something cool? Snap a photo. I only get a great photo every once in a while and I can increase my chances by continuously snapping away (yes I know framing and designing the shot is important too).
Power Bank - This is incredibly vital for me. I utilize my phone a ton to search for food and attractions and so if my phone ever ran out of power I'd definitely be screwed. Having a good power bank means I can charge my phone like 8 or 10 times which allows me to never worry about needing to find a quick charge.