JimmySilverrims said:

Also, how do you make it seem that Grevious meant anything to Palpatine, or at least enough to bring him back to life (apparently for a second time)?

Hm... how about replacing Grievous' eyes (not a hard thing to do) to make it look like it's Darth Maul ressurected? (Maul is after all, a very skilled warrior, it would be shame to lose him totally, and Palpatine visited Naboo just after he became Chancellor - a certainly good moment to retrieve the body). If we go the 'Dooku is Sith' route (it won't make sense in 'Dooku is a real rogue' route), it could be possilbe to insert some kind of a cameo in AotC of Grievous, of him being rebuilt and stuff (think Pirates of the Caribbean: Dead Man's Chest, when we saw clues regarding Barbossa's reappearance before we knew he would actually reappear).