I think the strength in depth we have combined with Pellegrini's fondness of tactical flexibility, I can see us rotating regularly throughout the league, the cups and the CL unlike Mancini (who opted for a first XI regularly).
If I had to choose two main starting XIs one would be a 4-3-3 and the other a 4-2-3-1.
4-3-3: Hart - Clichy, Nastasic, Kompany, Zabaleta - Toure, Fernandinho, Silva - Jovetic, Aguero, Navas.
4-2-3-1: Hart - Clichy, Nastasic, Kompany, Zabaleta - Toure, Fernandinho - Silva, Aguero, Navas - Negredo
I think we might opt for the 4-3-3 in CL games where retaining possession is vital. The 4-2-3-1 would be a deadly side against weaker league teams and in the cups.
It's hard to see how Rodwell, Nasri and Dzeko would figure regularly. Though Rodwell could probably clearly cover for Yaya for the African Cup of Nations and in the League Cup or in the case of injuries etc. Nasri (and possibly even Milner and Sinclair) could fill in for Silva, Jovetic and Navas. No real place for Dzeko though as he can hardly play alongside negredo (he's too similar).