I agree with many of the above so a few more not yet mentioned:
1. the adult world is inclusive of children
2. teenagers / young people have a good time without drinking tons of alcohol
3. serious respect for writers, artists, musicians etc
4. the political climate is far less conservative then...
OK Bseabrooke, I can suggest the park near Belgrano R station (which has a nice kids area, and cafes on the square), but since its forecast to rain for the next three or four days, maybe a day/time should wait till next week.
I have a 3 month old and also live in Belgrano with my partner. Only problem is I'm a dad and so don't seem to qualify for a mum's meet up in the park / mom and baby things, etc.