Well there's always Star Wars: Battlefront II! you can set up private matches, invite everybody in, play a few quick skirmishes and jump off. That's always been a classic favorite of mine.
War of the Roses was kinda hard to get into, but still a fun one. I imagine if you could get all your friends together and all run around in a group, working together against the opposing team, you could have a blast with it.
One last suggestion would be The Ship, the online community is mostly dead by this point, but with 8 people I think you could still have a really good time with it. Basically think the board game Clue mixed with the short story The Most Dangerous Game and turn it into a video game on a variety of boats. You all get a quarry at the start of the match and have to hunt him/her down while avoiding your own hunter, also taking care of some basic needs like hunger, thirst, fatigue, hygiene, kind of like The Sims, just to make sure nobody's just camping out in one area the whole game. If you're eliminated you become a witness until the next round and you can harass the other players and catch them in the act of trying to murder one another. It's one of the more unique multiplayer games I've played in recent memory and it's pretty sad that the online is kinda dead at this point. Still, if you've got a large group of friends like you mentioned, you could have a really good time. Plus, there's apparently a sequel that's attempting to be Greenlit right now after an unsuccessful Kickstarter campaign, I really wish em well, I'd love to see the concept developed further because it genuinely can be pretty fun despite some flaws.
If you guys do end up playing The Ship, send me an invite, I'd love to join you for the ride
My Steam name is Quady14