There is quite a difference in it being one or possibly 2 weeks as to where you could go at a relaxed stress free pace. The options mentioned by Buck are among the first that came into my mind [Yellowstone or Oregon, but another suggestion to throw into the hat would be the Sierra Nevada [Yosemite and Sequoia] combined with the Cali coast. [SF, Monterey, Big Sur].

I think you need to sit down with the family, open a good map and see if you can find one place that you all agree on and build your trip around that destination.