The issue in Spain IMO wouldn't be the kids or school (depending on the age of the kids - over 10 and you might encounter problems with the language) The big question isis it hard to emigrate to Spain and put your children in school there. Is the school free? I hold a British passport but my children are on an Australain passport.
WILL YOU BE LOOKING FOR WORK?
If so, think over 20% unemployment/ over 5 million unemployed etc etc.
Look at the stickies and do a search for work, unemployment, jobs, crisis etc and you'll see what I mean.
On the other hand I have no idea what the situation is like in Australia, but I seriously doubt it can be as bad as it is here in Spain