ST9: Insurrection
This low-key movie suffered from following the full-on action/horror of ST8 back in the day (My own opinion of it was luke warm originally). Frakes went the opposit way and made a film all about character and emotion (With hilarious comedy moments). When I watch this again now, it stands up with the best of the Kirk&Co films, also being strongly about family. Perhaps in it's small way it's the best NG movie.
Casino
As close to a sequel as a film can get without being one. Easily as good as 'Goodfellas' for me and perhaps a shade better.
Bill & Ted's Bogus Journey
Far better than the first. It's funnier, more creative, crazier, chock full of pop-culture gags and ends with that crowd pleasing concert.
Gremlins II: The New Batch
After all the horror thrills of the first movie have faded it's the wicked corporate/media satire of the sequel, that has stood the test of time.
Army Of Darkness
I know this has many fans but for me it's so massively superior to the first two in every respect, that it feels underrated.
The Karate Kid, Part II
Far more heartfelt and emotional than the first, looking back on Mr Miyagi's sad past. The Tea ceremony scene is simply beautiful.
Short Circuit 2
I probably go on about this one but wow it's a near perfect romantic comedy for me. Joy on celluloid.
Hot Shots! Part Deux
Ludicrously silly with the jokes flying in all directions after they wore out most of the Top Gun gags in the first one but so good.
Er, think that's about all I can think of.