You didn't say how old your children are...
But if they are on the young side, I would not advise having
them watch Star Wars Episode 3 until they are older. Lots of
dark themes, lots of heads and other body parts getting sliced
off by light sabers (is killing someone with a laser blast less
violent?), and a whole bunch of young Jedi slaughtered.
And I would not recommend Satr Wars 1 simply because it
is awful, and not just due to Jar-Jar Binks. I also blame the
kid who portrayed Anakin and the deeply uninvolving story
line.