I think 12-15k on a income of 100k is a lot but obvs it depends on mortgage & age of children.
Surely it also depends on things like adult ages, savings, whether people have inherited?
We earn well but less than 100k, probably about 70-80k joint (varies as DH self employed and pays variable dividends as cash, with some going into pension).
However, we both bought property when young so have been mortgage free from when we married 21yrs ago. We had some childcare but not extortionate (I am PT) so have always had reasonable disposable income, a lot of which we invested.
Most summer hols when kids were younger were in a touring caravan, home and abroad, mixed in with half term trips to hotels, cottages, Centre Parcs but no long haul.
Our first long haul, to Canada, was 4 Yrs ago and we did a road trip to W USA last year.
So.....we are now in our 50s and over the last two years our savings have been boosted by an inheritance, some endowments and 2 compulsory share sales.
Thus we were able to splash out on last years USA holiday, booking 2 rooms in many hotels and doing activities like helicopter flight over G canyon. It cost around 15k for 4.
Going forward, as we are moving out of school hols, we will be able to have similar holidays more regularly. It will probably be every 2-3 yrs whilst DC want to come with us, maybe 1-2yrs when just 2 of us going. But we will use caravan in between, which is a reasonably cheap holiday once it is bought.
I would never pay £400/night for a hotel, but we did get an upgrade in Vegas last summer, so DH and I could be on same floor as DC, and we ended up in a very posh suite. It was nice, with a wrap around balcony giving great view of strip and fountains, but I still wouldnt choose to pay extra to stay in it!