Oh, we do it every now and then.
I had planned to have Owen as Anakin's friend as well. I thought of making Anakin a smuggler who's helping the Seperatists, not out of any particular sympathy to their cause but just in order to make a living. At the beginning of the first movie he would be captured by Obi-Wan, who spots his exceptional strength in the Force and offers him the chance of a new life as a Jedi. At first he's happy to accept, but as the war etc. take their toll he becomes more and more disillusioned with the Order.
As for Padme (or whatever Luke and Leias' mother is called), she would be the daughter of the king of Alderaan. Anakin could be assigned to guard her along with Obi-Wan (as in AotC) and they would gradually fall in love, but for a reason this time. (Maybe he could save her from some kind of danger - yeah, I know it's clichéd, but that's the best I can think of for the moment.)
Anakin then leaves to fight in the Clone Wars, during which Padme's father dies; she accedes to the throne and is pressured into an arranged marriage with Bail Organa, another important noble. Anakin gets to hear of this and secretly visits her just before her marriage to beg her to reconsider. They spend the night together and he wants her to run away with him, but she insists that she must do her duty. He leaves, bitterly angry and disappointed, and she then discovers she's pregnant...
With the Sith, I prefer to have them as the anti-Jedi, followers of the Dark Side (as in KOTOR). But it could be that Palpatine has discovered how to resurrect the original Sith species by cloning their DNA, and that these are the clone army. (We never get to see what they look like under their uniforms, after all.)