"Or we could just let Bunning finish his term and McConnell run for re-election to simplify it. How's that? :-)"
Simpler, yes, but not as Machiavellian. : )
And, of course, it would give Democrats a running start against whichever Republican runs to replace Bunning in 2010 (assuming that he will not run for reelection). But if the Democrats think they are running against McConnell instead of Northup, they'll probably nominate Lois Weinberg or someone like that instead of a top-tier candidate.