Brisbane
Onboard the very first flight of United's newest route to Australia, San Francisco to Brisbane (SFO-BNE). Ended up on the very first return flight as well the next day, so actually was on both inaugural flights for this route. While I've been on other inaugural flights before, this one was an even bigger deal than usual, as The Points Guy covered in detail.
Day 1 - onboard UA 96, United's inaugural flight from SFO to BNE, as well an unexpected invite to the private pre-flight party beforehand inside the United Polaris Lounge SFO.
Day 2 - arrival in Brisbane with more inaugural flight festivities, plus being a tourist.
Day 3 - inaugural return flight to SFO on board UA 97, and yes, more festivities.