Teaching them to be nice is good, and teaching them to be kind may be even better.
Of course both is most desirable but if you can only have one I'd choose kind.

Sympathizing with a friend or guy on the block, telling them you feel bad for them and if they get in a jam to call and you may be able to help. That's being nice.

This is being kind...


They may never be in a position to do this but I hope they would help if they can.
No angels will sing hosannas or spread palm fronds, they may not even get a thank you, but usually they'll feel good.