Seoul is a very modern user friendly place.
Almost everything is usually walkable within your "village" & it’s easy to get the things you need on a daily basis. There is always an open 7/11 at arms length day and night!
Between neighborhoods, there is a great public transport system.
you can easily do without a car. Its safe, reliable and relatively cheap.
For a big western style economy, South Korea is cheap (comparatively to say Tokyo) and there is entertainment/food for all budgets.
Beautiful landmarks (palaces and temples surrounded by peaceful parks) & Big parks/woods/river walks within the city and nearby.
Healthcare is good and affordable, some surgeries have entirely English-speaking medical staff, your medical insurance helpline will be able to assist.
Most people understand english and will make an effort to help out. Its worth making a small effort to learn basic civilities, they are so gracious and won't hold your Faux-pas against you. The basic rule is to never loose your temper/show frustration publicly, its all about keeping face and negotiating like in most parts of Asia.
Did you see the expat woman website? lots of usefull info.
expatwoman
here is a link to all international schools
shools
The british school is north of the river with a good range of accommodation nearby. The business/shopping/old city are for the most part in this area.
You could also consider Dulwich college which is south of the river. Lots of pleasant areas in this part of town, lots of expats here too with the french school also in the area. Could be good if your husband works in/near the gangnam district.
I would advise against living on one bank and going to school on another as the traffic can be a killer and they could sit on the school bus for a while.
Schools can usually tell you about bus routes so do ask if you need to factor that in when looking for a place.
HTH