Suggest a long haul - August with Teenagers please

[Alwayssupportingdifference]

Looking for sun, sea and a bit of sight seeing. Budget £12k for four people.

Australia, Thailand, America considered, possibly Bali. Looking for resort recommendations. Maybe a short city break followed by resort.

Def no driving though so no fly drives. No theme park type stuff either.

Railay Beach in Thailand is beautiful.

San Francisco?

What sort of sight seeing - museums?

New York is good for teens but possibly too hot in August to be enjoyable.

It'll be winter in Australia in August so I'd avoid that!