Yes, of course it's about the individual first. BUT, I find it helpful to see if I'm within the range of "normal" both to check that I'm not asking too much or too little of my kids, yk? DC was an only for 10 years, which maybe is a factor, I don't know. She has asked me to accompany her on her school overnight (one hour from home) every year until last year. She does want to go...but I was not the person who talked to her about it first (her aunt broached the subject). I was neutral when I asked her and she said she wanted to go but wondered if she could go for shorter.
BTW, I'm not sure if I consider this a "once in a lifetime opportunity". Other posters called it that - not me.
There are two threads going - one where I asked about flying (this one) and another more general one about this trip in particular. I'll try to keep the rest of this thread on the flying issue (because I didn't mean this to be all about me and this particular trip). We can continue the other stuff on the other thread....
Like I said, I flew alone at 12, domestically, nonstop, short flight. The flight was fine. It was much anticipated -- hyped up for several years. I liked how that was done and feel that 12 was the right age for me. I voted 12, even for international nonstop just because I feel the world is getting smaller and kids travel more (DC has already been all over the world and lived on two continents).
My sister flew at 15 to Europe to visit me. She traveled with a friend but they traveled all over together just the two of them. I thought that was a fine age for that.
Back to the "it depends on the individual" my other sister traveled to see me on several occasions and was really not ready to make the most of it and be a pleasant guest.