A lake front house on Flathead Lake in late July would be my strongest recommendation. The lake itself is amazing, but the surrounding area (including Glacier and Waterton) are really special that time of year. Hawaii is great too if not traveling in summer.

Cannon Beach, Oregon is awesome too, but that is a summer destination

Being from CA, the CA suggestions are kind of meh, though I would recommend Tahoe or Yosemite for a long weekend, just maybe not a whole week.