Thanks for the replies, keep them coming LOL
They will be in the States for 20 days, and with their host family for 10 of them. The rest of the time will be Disneyland etc.
We were supposed to get more time to make up our mind about where they wanted to go, not sure what happened there? But I think it's always good to get some local knowledge
How cold does it get in Portland and Seattle in Winter? 'We don't live in an area that gets snow so I don't know if they would have enough warm clothes.