"The hallmark of the Grand Tradition story was that they were fun to read. Grand Tradition stories were pure entertainment; they were adventure stories found nowhere else. Grand Tradition stories were written in every SF motif (horror, noir, pulp fiction, first contact, spaceship, alien invaders/visitors, political intrigue, hard science fiction, etc.) and they embraced all of the familiar SF tropes. Grand Tradition stories often included social/political commentaries and they opened windows on worlds we could not otherwise see, but these elements were part of the subtext. The foreground story was the adventure, the wonder, the delightful romp through a strange and wondrous universe."

You can read more about Grand Tradition Science Fiction by visiting the Fantasy Cafe blogsite.  
http://www.fantasybookcafe.com/2014/05/guest-post-grand-tradition-science-fiction-by-bascomb-james/