Seasonal jobs that might turn permanent - any advice?

A retailer and two warehouses near Pittsburgh are hiring seasonal staff. It has been a long 9 weeks. Hours ramp up in the coming weeks. Which employers treat seasonal workers well?

Keep a list of supervisors' names. A reference from one of them helped me land my next job.

Thanks for writing this out. I went through something close to it last year, and it got easier once I kept a simple log of every call and form.