Arkham Horror: dominant personality issue?
I've successfully played Arkham Horror several times with non-gamers (and myself being the kind who tends to push others around). My tips:


Think of yourself as the GM.  You'll be the one who keeps the game moving, and your primary job is making sure everyone is having fun.  As much as possible, give your character the supporting jobs and let them play the game.
Simplify the game for them by focusing on the concepts, not the rules.  My super-simple explanation of the game to get someone started: 


  We win the game by sealing gates.  You need 5 clue tokens to seal a gate, but sealing a gate is dangerous so make sure you're ready.  You'll need 4+ stamina/sanity, and a weapon or two.  You can get weapons in a bunch of ways, but the easiest way is to go get some cash.


Yes, this is a gross over-simplification, but it gives them a roadmap for their character and a sense of progression, instead of random wandering around.
Let them play selfishly, even if it's not an optimal strategy.  Nothing ruins a new player's fun like having to give up a Tommy Gun because someone else could use it more effectively.  Each turn, they should have something to do to try and make their character more awesome: get an item, get a monster or gate trophy so they can trade it in, etc.
Give options, not orders: "You could go to the Newspaper and try to get some money, or you could go kill this monster, or go over here and help someone else" etc.  If they make what seems like a bad choice, oh well, the game can still be fun even if you lose.
Don't be afraid to bend the rules in the first game.  An early monster or rumor draw can really make a game impossible.  I'll often quietly redraw in those cases if I'm playing with inexperienced players to give them a chance.


Overall, Arkham has been a great cooperative game for everyone I've played it with.