Price4,
with your children in Nido (our daughter is moving there next year too from her current school), you can live anywhere in La Dehesa, Lo Barnechea, Vitacura or Las Condes, as the furthest away will be a 20 minute or so drive (depending on traffic. Nido starts later than the other schools, so most of the heavy traffic is missed). Nido is in La Dehesa, so that would be your most convenient choice of suburb. The area has a lot of expats, most of the diplomatic staff live around there, good shopping malls and is a safe environment, mostly houses. Las Condes is great if you are after an apartment instead.
The school also has an safe and reliable bus service (external contractor though, but that's the norm here), which picks and drops the children from your front door.
Most people we know, do a reconnaissance mission over here to find a home before they pack up and move. It is much easier being here and inspecting houses, than to find it over the internet. The real estate sites are not that great, but
http://www.corredoresintegrados.cl/is a good place to start to educate yourself about pricing.
We moved here and first stayed in a apart-hotel (
http://www.boulevardsuites.cl) while we looked for a house. We had to stay there about 6 weeks before our house was ready and our container arrived.
There are a number of relocation consultants (I can't name any here, as I would probably get a black dot next to my name) that speak good English and that cater mostly for the Nido crowd. As much as I think most relocation consultants are a blatant rip-off (the fees they charge are absolutely outrageous), I found that the good real estate agents don't speak English (the ones we met that did were atrocious), so unless you are fluent in Spanish (if so, I can give you the name and number of our real estate agent), you will need some help with finding a home.
Let me know if you have any other questions, I'm happy to answer.