Thanks for the previous advice regarding a replacement HVAC system. I've decided on the Carrier Infinity system for 2 zones and the contractor came by to go over register and return placements. He is giving me some flexibility with the actual placements (since we need to deal with lighting and fire sprinklers as well) and I'm hoping to get some advice on optimal register placements.

We are in So Cal, so a more cooling oriented environment. The ducts and registers will all be in attic and ceiling. The house has new replaced dual pane / glazed windows and sliding/french doors.

I've done a little research and some people say you should place the supplies along an interior wall, but direct the flow towards the windows/doors, but others have said you should put the supplies over the the wall with the most exposure so it doesn't affect interior temperatures as much. Any thoughts or suggestions?

Also, we will only have 2 returns (one per zone). In the bedroom zone, the option is to have the return in the master bedroom (4br house), or in the main hallway. We tend to close the master bedroom door in the evenings. Is there a recommended place for the return and will we need "passage ducts" (connecting ducts above the door so air can pass from rooms to hallway) for each room? And should the zoning thermostat be located very close to the return?

Thanks again, I really appreciate the help.