I hope I can get some more ideas than on the normal holiday board. Sorry for the length.
DD will be 18 next July and sits her A-Levels. She has ASD, previously you would call it high functioning. We are going in circles to find a holiday destination to celebrate her exams and her birthday.
I think it's easier to say what doesn't work:
Heat - none of us likes it, so everything south of the Alps is a no-go
No ships - DH gets sea sick on most boats/ferries/ships
No beach - DD hates the feel of sand and the noise of waves
No AI resorts - too many people, too much noise, too unstructured despite working out a schedule prior to going with a mix of quite days and sight seeing. The mayhem in the restaurants may have pushed her over the cliff as well.
No group trips as she would be masking all the time and we have a fall out
Due to some medical issues with DH where we don't know exacly what is causing it, we may not be able to do anything strengthnous like high altitudes, hikes or humidity.
We looked at Costa Rica - too many changes when you book a tour unless you just go for 2 center and we feel this is a waste. SE Asia is a big no from DD, safaris as well.
We did east coast US last year and it worked but she really wants to have at least one drink at her birthday so that's out.
She wants hotels but with table service, so no typical AI resort. We are s/c this year in Germany and she said it's fine (and I believe her) but I know where she is coming from. It doesn't help that thanks to a family problem abroad we are spending quite a lot of time s/c and I know we are all a bit fed up.
I am thinking I am looking for a unicorn. We thought about Iceland or Scandinavia, with a absolutely tailored tour, any recommendation of provider? Happy to self-drive but not a new hotel each night.
We all love history, DD also loves animals. Nature would be good and I love the sea/large body of water.