They Voted for Bush in 2000; Kerry in 2004
I suggest a series of ads (if they would be willing to go along) of prominent people who have endorsed Kerry saying they supported Bush in 2000, but now are supporting John Kerry.
I'd start this with Lee Iococa, who did ads for Bush in 2000 but now supports Kerry, and have him talk about the economy.
I'd include the retired generals and national security experts who have endorsed Kerry, the Nobel Award winning scientists, the economists, and business leaders. This would highlight the major issue, and have people attack Bush for his failings, without Kerry appearing to be negative. Such a series could also generate some media buzz, and we've seen with recent ads how the media can greatly increase the impact of ads.
As long as I'm laying out my fantasy ad series, I'd conclude it just before the election with Donald Trump repeating what he has said in interviews, both that the economy does better under Democrats, and that he'd fire George Bush for his handling of Iraq.