PER has more day trips as the majority of the work is mining related. I'd say the operation is similar to say National Jet or Skywest with different conditons obviously.
I'm not sure about the east coast differences- GAFA or Bunglerat may know. Apparently BNE gets better trips and some more days off but this is only what I hear others say.
Ultimately the bidding system allows you to try and target what you want.