My friend was one of the people who founded this non-profit, The Milestones Organization. This is the second year that they are having a small conference for parents and teachers of children with autism. This includes children who are high and low functioning, and also children with other forms of PDD, like Asperger's Syndrome.
The conference this year is June 21 and 22 at the Landerhaven Country Club in Mayfield Heights, a suburb of Cleveland. The whole conference costs $225, but you can choose to only attend one day for $100. The conference is pretty mainstream in that most of the speakers are professionals (though the keynote speaker is a parent). Nevertheless it's a great opportunity to learn about what the current thinking is on autism, and to meet other parents of autistic children in the area. My friend has had a lot of success with various kinds of speech and behavioral therapy, largely because she has been good at connecting with other parents and learning what they do.
If you can't afford to go to this yourself but have been having trouble with your children's teachers or school officials, send them the information about the conference. They can get professional credits for going and you will benefit from them knowing more about autism.