There was absolutely nothing wrong with teaching the Vienna to kids. It's a good, classical line. As some others mentioned, it's a gambit line, which is important for kids to learn. Gambits teach kids not to be too materialistic and to value development. Of course, there are more main stream openings that kids can learn, but that doesn't mean the Vienna was a bad choice.
This is a real problem with seeking advice from the internet. The best answer you will get will usually be the staid, safe answer, wrapped up as the only possible response.
Chess teaches us to think independently. Trust yourself.
@Ezamit
Don't listen to these people!
You are better off getting a coach or coming up with a plan yourself.
It is completely obvious people on this forum have no clue what they are even talking about.
They are trying to agrue in good conscience that the Kings Indian Attack & Kings Indian Defense are considered positional?????
Never in a million years has it been recongized as a Positional opening.
It has always been considered a Tactical/Dynamic Opening.
All openings in chess have both positional and tactical elements.
However, one element often dwarfs the other.
The KIA & KID are more recongized as tactical elements than positional ones.
It is completely obvious all they feel like doing is giving false information.
Jengaias even went as far as to say Garry Kasparov has wonderful positional skills.
Yes, Garry Kasparov played the Kings Indian Defense to positionally squeeze his opponent into submission!
What a moron!
What ever you do don't listen to them!
You are better off going to a professional.