I can understand where you older sister is coming from, to me there isnt the "magical" chemistry that Han Leia, Luke and Chewie had, only in parts of Clones and in Sith does the chemistry come near (people may agree/disagree), and the creativity nothing really comes near the famous opening sequence of Star Wars or the Introduction of the SuperStarDestroyer in Empire in my opinion in the first two, and for emotion only sequences in Sith comes near the binary sunset in Star Wars or the Vader revalation and I feel the pacing of the first two prequels is poor and drags compared to Star Wars and Empire,maybe Jedi, the only one i feel with proper pacing is Sith which I think most O.T fans, and agree personally is the best and the closest film to the O.T

I do feel Lucas was stuck between a rock and a hard place having to tell a story which was more "serious" for Star Wars and more serious than the O.T and having to keep it entertaining and kiddie friendly, only in Sith, though the others had moments, did Lucas finally pull it off, keep the serious side of the story, but keep it entertaining etc.