Slumber Party Alien Abduction, Jason Eisner, (short, from otherwise not-great VHS 2) is totally delightful, fresh, and nostalgic.
I have shown this at no less than four scary-movie-dinner parties. It's so silly, gross, funny, and good.
Cabin Fever, Eli Roth, 2002
I know, I know, Eli Roth, but it's both stupid and clever and also, it's legitimately visceral.
Jennifer's Body, Karyn Kusama, 2009
Good story, good acting. Cody's style of dialogue is improbable but somehow not distracting (maybe it's occasionally cringe-worthy, but only occasionally). Adam Brody is a dead ringer for The Killers dude, and he should be in far more films. Would be good paired with Slither.
Grabbers, Jon Wright, 2012
A small town in Ireland is attacked by a man-eating monster and the only way to ward it off is to maintain a high blood-alcohol content. It's good!
The Cabin in the Woods, Drew Goddard, 2012
Murder Party, Jeremy Saulnier, 2007
Clever enough, very low-budget, and funny. Go in with appropriate expectations. I mean, it's called Murder Party.
I think low-budget, low expectations, and high-concept is the way to go. The Purge, Insidious (seriously though, only the first one), and Paranormal Activity are at least pumping some life back into the genre, and they'd all be fun to watch with a group.
Nightmare on Elm Street 2, Jack Sholder, 1985
I know it basically ignores like half of the rules that the first movie establishes, but it's fun and has a terrifically charismatic lead, plus some fun (and, for the time, progressive) undertones and anyways, if you are at a party you are only half-paying-attention.
It's...darker than you'd expect it to be, and probably better, too.
This is totally a solid remake, with great acting and a script by Buffy's Marti Noxon. It's often overlooked, for whatever reason (I've personally forgotten its existence several times). But it'd be a reliable and fun choice for a group situation.
A really fun classic that would pair nicely with They Live.