I wasn't so sure about that one, you're right, it's not an Impala. It's not a GTO either though, it's a '65 Tempest (85% sure this time). GTO was an option package on Tempests for the first few years, but it wasn't available on sedans in '65. It's possible that the B pillar is behind the guy's arm and it's just a really really long coupe (
link), but on GTOs that badge in front of the taillight just says 'GTO', and it's too long for that.
It looks to short to be 'Tempest' either, maybe it says 'LeMans' or 'Custom' (other trim levels).
While we're correcting me
this one doesn't seem right either. Absolutely everything about it says '55-'56 Cadillac, and it should be a Sixty-Two, since it's a coupe, but I can't find one with quad headlights like that. Maybe it's some extra-special rare version, and that's why it's at Monterey.
This is a case where people with knowledge and experience could show their advantages over someone who's just flipping through
a really good reference book, which is what I've been doing.