In response to all the grown-ups complaining about children here, I can only say good luck with that adults-only planetarium business concept.
Maybe I'm not as cranky as you all because we found it's possible to visit the museum part of the planetarium without paying the exorbitant prices for a planetarium show. There is an underground tunnel which connects this to the Biodome (which also has a large free exhibit downstairs). Our two kids were happily entertained (probably not educated) here for an hour or so, which made us happy. It's a nicely designed space with a reasonably priced cafe, and I can imagine it would be a great place to spend time in the colder months. So yeah: free, kid-absorbing, clean bathrooms, easy to get to, and therefore not really anything to complain about...