Hey tgo15,
It really depends on what kind of life style you want in Japan.
Living in the middle of Tokyo can be really expensive. Decent 2-3 bed room apartment cost 200,000-300,000 jpy.
And many people in Tokyo don't even own cars because parking costs about 30,000-50,000 jpy.
Living near Narita could reduce cost of living to 1/3 of Tokyo and you can easily own a car.
But Narita is far from Tokyo and might feel bored if you are city kinda guy.
I would personally suggest near Kaihin Makuhari area which is between Narita and Tokyo with good mixture of city and relaxed life style.
There is also a international school. There is also a direct bus to Narita which takes about 40 mins non-stop.
Town itself is very safe and clean. Cost of living would be aprox half of center of Tokyo.
Don't even think about Yokohama. Commuting to Narita will take almost 2 hours although the city is very nice.
Let me know or PM me if you need other info. Cheers.