The problem with Betrayal at House on a Hill is the editing of the rules. Some haunts reference a rule that isn't explained anywhere else and the players are left to guess what it's supposed to be. There have been a few times where we ended up in a draw because something in the haunt was broken. If they had edited the haunt sections of the rule books and made sure that all rules were referenced in the main rulebook, the game would go more smoothly.
If everyone is familiar with the game, Twilight Imperium can fit in the time frame. However, I'd they aren't, that can be 16 hours from the time you start figuring out the rules. Even longer if you read the rules, rather than watch a video (nine of which I've seen are comorehensive).