I use it extensively once im at a destination to generate ideas for where to go and what to see based on my interests and likes and dislikes, e.g "I'm in X city for the next 3 days, and I enjoy hiking and wwii history, what are some things to do?" "my mother in law and wife want to take a daytrip in region X, whats a good day plan given my MIL cant walk or hike far and my wife wants to take photos of scenic views?" I've gotten some great off-the-beaten-path suggestions this way.
But yeah im not using to book flights or hotels.
That's how most of us use AI for planning vacations, i.e. as a (better, by this point) replacement for Google Search.