I would imagine one of the most pressing problems in the aftermath of the teacher's strike will be to assuage the anger the parents have towards the teachers. By striking, the teachers have derailed a smooth start to the school year, have delayed the learning process, caused children to become upset, and messed over working parents in terms of their child-care arrangements.
The best remedy I can come up with is for the PTO to get the prep work done and be fully prepared to move forward at light speed to get activities such as parent orientation/open houses/information evenings, production of the class rosters/school directory, and preparation of fall events (like carnivals) back on track.
The faster the school environment can appear to be "back to normal", the easier it will be for parents to let go and move on.
How about a "Looking forward to a great year" breakfast for the teachers on their first day back? A teacher's strike is hard on everyone, and it's great that your group has recognized that and wants to help. Something as simple as fresh hot coffee and tea, bagels and spreads, donuts/pastry, can really show the teachers that they still have the support of the school, and the PTO. I'd get the principal involved too. Have him or her there to welcome the teachers back, along with the PTO volunteers.
If a welcome back breakfast is something your group already does, you can try jazzing it up a little with some fresh flowers, or little decorations.
Our teachers union has recently gone on strike. Our building PTO group would like to start planning ideas to heal our school community once the strike ends. Any ideas would be greatly appreciated!