We recently flew from Guam to Bali on Eva Air, the official airline of Hello Kitty. We travelled stand-by, and the staff at Eva Air were very helpful when it came to making our stand-by travel arrangements. It was definitely a kid-friendly airline with Hello Kitty products everywhere. Even the toilet paper was Hello Kitty.
My only complaint was that the flight attendants came through the cabin once to disperse drinks and snacks with only one quick follow-up to pick up trash almost immediately after serving drinks. We had to sit with trash on our trays for the rest of the flight, and when it came time to land, the flight attendants told my kids to just close up their trays and hold their drink cups and trash in their laps for landing.
Despite that one awkward detail, the airplanes were comfortable, and the entertainment systems offered an adequate selection of movies. It was the most efficient way we found to travel from Guam to Bali, though the connection in Taipei was tight, since we had to run from one end of the airport to the other and back again in order to check in at the transfer desk between flights. Luckily, the flights were running on time that day, and we made it with a few minutes to spare.