Palmer's wife is fantastic, but for me the MVP supporting actor (besides the great Xander Berkeley) is Carlos Bernard as Tony Almeida. Elisha Cuthbert stayed on the show past this, as I'm sure you're aware, and her stories got even stupider, as I'm sure you're aware.
Aside from amnesia, the worst, most time-wasting trope this show indulges in time and time and time again is "Jack Ruby-ing" people -- they have the suspect in custody, they're carting him away, the chase is essentially over, then out of nowhere somebody just snaps and murders the suspect for no reason (normally someone who didn't know they were working for the bad guys and feels betrayed). It never stops being super dumb, every single time it happens.
If you end up going through the whole show (I know you will), just keep in mind I gave up after season 5. There's also a TV movie, a revival season, a reboot, and apparently ANOTHER revival season on the way? It's never going to end at this point. Is that why you chose it?