^Just read your reply after posting mine.

Actually, it might be a good idea to use ROTS as the frame narrative, with a few flashbacks to the events of AOTC. There'd be a few tricky pieces, such as establishing Dooku's identity.

When Palpatine reminds Anakin about what happened with his mother and the sand people, you could easily insert a flashback sequence to those events.

You could insert some of Anakin and Padme's backstory right before Anakin's first nightmare about her death, though I can't rattle off any specific suggestions.

Eh, it might help make it feel like a more cohesive single film... because it basically would be to start with.