Chances are your school is either one of these:
Kennedy School / West Island / I something or the other or Kellett
Kennedy Town / West Island / Kellett kids are mostly from the Southside with a majority of them from Pok Fu Lam.
Forget about your commute and consider the kid's commute / social life....
Quite a few options in Pok Fu Lam - some of them have frequent buses to either Kennedy Town or HKU MTR station. From there, the commute to Kwun Tong is not too bad - 30-45 mins. My 13 year old does it every day on the MTR to Kowloon Bay and I'm sure you can figure out how to deal with it.
Places like Scenic Villas, Belair, Baguio Villas and the smaller other communities / developments are not "expat ghettos". Good mix of long term local population (80%+), long and short term expats.
Avoid Repulse Bay / Tai Tam / Stanley - there is a lot of traffic on that part of the island and you'll be restricted to the Aberdeen Tunnel which is congested at peak hours.
Some people like Kennedy Town - I don't like it. Apartments are newer, lots of construction and just too crowded for me. Parking is a mess ....
Get a place which has good parking ... the morning drop off to school in the car will pay for the car park in terms of school bus savings.