A little radical idea for ROTS:
Push the Grievous plot back and let Cody shoot Obi-Wan during the chase scene so that Grievous survives.
Then cut Palpatine finding Anakin and use the hologram scene with Darth Sidious and Grievous and alternate Grievous line to: “…the loss of Skywalker”

Because Order 66 doesn’t happen before Anakin’s turn and Windu went to make sure that Palpatine returns his emergency powers after Grievous death, let Palpatine declare the empire as a reaction to the separatist attack on coruscant. This would explain Windus move against the chancellor and would also play well into Padmé’s politics plot.