I got two excellent board games: Hunt for the Ring which is very interesting and we play it in-family with my wife and kids. And the amazing Eldritch Horror for even more fun & excitement as we try to save humanity from all the eldritch horrors that surface.
From what I've read, I think my kids are not quite old enough for Hunt for the Ring; they are 7 and 10. How old are yours?
I've played Arkham Horror, but not Eldritch. I really liked Arkham. Do you have any idea how they compare?
Mine are 8 and 10. In Hunt, one player is Frodo and does the hidden movement, while the Nazgul players try to deduct his location. I always play Frodo myself and try to balance my actions accordingly, so that the kids have a chance; a rather simplified version, where I do not always take the optimal action, as I would in a normal game. But, I think that as the kids get more experienced with the game we will be able to play normally. We have also played Cluedo: Star Wars and a couple of other deduction games, but Hunt is more advanced and complex; and better :)
As for Arkham Horror, I have not played it but a friend of mine, that is also in the Eldritch group, did: he says that Arkham is more complex, but he likes Eldritch better. For me, Eldritch provides the perfect bridge between a toned down boardgame and a standard RPG like Call of Cthulhu; it is ideal for our group of adults that have limited time for sessions and no time for preparing an RPG as DM.