No matter how far away you move, it's going to happen on occasion. Either her parents are going to come visit, or she is going to insist on going to see them. So how do you deal with the in-laws? Maybe the best way is to not view them as in-laws at all.
Remember this: the woman you are madly in love with came from these people. There have to be some good traits in them (seriously, if they were that bad even she wouldn't want to spend time with them). Look for the positive.
Don't get pulled in to a match with her dad where you have to try and prove that you're a better provider for her. He raised her. He changed her diapers. He loved her first. Let him have that. She's going home with you when the visit with mom and dad is over, so in the end, you still win. It really isn't a competition at all. He just wants a little honor, so let him have it.
A disapproving mother-in-law is even more frightening. You might be afraid of what she's saying to your wife while you're being distracted by dad. The solution is simple. Talk to your wife about your concerns. Communication is sometimes downplayed as not being manly. But if your wife knows how much her respect means to you, she may be the one to shut her mom up if the dogging starts. There's nothing you can say to shut down disparaging remarks from your in-laws, but if they know their daughter isn't going to take it, then they'll have to play nice. Make sure the Mrs. knows you need her on your side (not that there are sides, right?).
Of course, there are other in-laws too. If she has a brother, the key to being in his good graces is to find out what he likes to do and hang with him a little. Go out for drinks, play some golf, whatever. Do some manly stuff. Just don't be an idiot and talk about women with him. Most brothers-in-law won't actually kill you if you hurt their sister, but they may want to fight, and they certainly will speak their mind about you a lot more freely than her parents.
One last piece of advice. No matter how annoying of a sister-in-law you may have, you can't get in between your wife and her sister. If you have a brother, then you probably understand what I'm talking about. Whatever the sister throws at you, just take it. You can tell your wife you don't appreciate it, but if you don't fight back or try to keep them apart, she will appreciate it.
In the end, the best way to deal with in-laws is the best way to deal with everyone. Figure out how you would want to be treated if you were in their shoes, and then let them have what they need. You're not being a doormat. You're taking the high road. Your wife will love you for it.