I would prefer Cary Grant in pretty much anything, but I don't seem him doing 'staid'. He's great at goofy, romantic, or stalwart (he was even a war hero in Destination Tokyo, which was unusual for him), but I don't recall him as staid and confused in any of his movies, which was Henry Fonda's bread and butter.

If you've never seen The Mad Miss Manton, it might make you feel a little different about Henry Fonda. Maybe.