Seriously though, I think the only thing any of his kids would have going for them is the surname, and that's only really gonna be a sales-hook for Reagan groupies, a category which even at the height of his popularity managed to exclude 40% of the electorate, with firebrand enthusiasm for the man only waning as the years went on.
So, just confining ourselves to Republicans, Maureen, Patti and Ron are absolutely unsellable to the base, for reasons of ideology and ballet. That leaves Michael, who was apparently a stalwart conservative media star. Don't know how effective he'd be as a campaigner.