Wish I could help you re specific places/projects but I don't really know of any that would be specifically kid-friendly. However, both countries are pretty family-oriented and kid-friendly in general, so if you are dealing with locals and not transplants, I'd say you're pretty likely to find people/places who would be fine with having kids around without too much trouble.
How old are your kids? That might be important.
Also, what kind of place are you looking for as far as an ideal place to settle? Weather-wise, community-wise, convenience-wise...
Do you speak Spanish or Portuguese at all?
Here on permies.com there seems to be a lot more going on in Portugal than in Spain. I think that may or may not be true in fact. Property is probably cheaper as a rule in Portugal, so good for permie transplants, and I think the Portuguese tend to be more confident English speakers than the Spanish so they may post here more often. Don't forget the "Iberia" forum, which is where you'll find all the stuff related to Spain & Portugal.
Here is a permaculture website for the Iberian peninsula:
http://reddepermaculturaiberica.pbworks.com/w/page/13844757/FrontPage
It at least gives some contact details of a lot of groups and people to contact. I'm not sure how up to date any of it is.
One center that is active and may be able to hook you up with people is:
http://www.permacultura-montsant.org/
in Catalonia (northeast of Spain).
Good luck and have fun!