I know there's a huge choice!
DSD has shown an interest in going to America next summer for a holiday. I've only been to north California coast, but she and DP have been to LA and New York, Boston, Cape Cod etc. DSD will be 21 next year, so we're not talking theme parks and doesn't have to be child-friendly.
I love holidaying with both of them and would be interested to try somewhere new - I usually default to Greece. If you've been somewhere that you think would be fab for two weeks in August (school holidays only for me), please suggest.