Maybe you could think of Episodes 1+2 and the Clone Wars CGI as a trilogy, and Ewoks:Caravan Of Courage, Ewoks:Battle For Endor and Return Of The Jedi as a trilogy...
Now, take them away and just look at the middle three: Revenge Of The Sith, A New Hope, The Empire Strikes back.
It's much more satisfying if you just watch those three as a trilogy; it's a touching tale about a brave Sith lord who overcomes the handicap of having his legs and arm burnt off, kills Obi Wan Kenobi, cuts Luke Skywalker's hand off and lets Boba Fett sell Han Solo in carbonite to Jabba The Hut. Beautiful!