A Santorum/McDonnell ticket would have a native of Virginia who is a resident of Pennsyvlania teamed with a native of Pennsylvania who is a resident of Virginia.
McDonnell is the father of five children (including a set of twins); Santorum of course has 7 living children (and one deceased). I don't how far back you'd have to go to find a ticket whose families included 12 living children--perhaps the 19th century.
Rob Portman is another name sometimes mentioned. He is a Methodist. He is currently senator from Ohio but I don't know if he would be able to guarantee that his state went for the Republican ticket.
I’d like to see Santorum/Thad McCotter simply for the comic relief a McCotter/Biden debate would provide. The proverbial “one legged man in an ass kicking contest”.