Obviously everyone's experience varies, but we've travelled extensively with our 8 year old and honestly she just doesn't remember most of it. I think they get more out of it when they are a bit older than 6.
Having said that, I think it could be really amazing to spend a year in DC, or NYC, at least for education outside of the classroom. If it were purely lifestyle we were going for, then I think Hawaii or California could be pretty amazing.
Unless you have dual nationality you'll probably find its quite difficult, if not impossible to live for a year in a foreign country without having a work visa sponsored by a local employer. If that's not an issue for you, I'd definitely recommend Sweden, which has an amazing lifestyle, and you can get by to an extent without learning the language.
