Mike -
What Gary said !!!
As for me, I just moved so am re-building. The town ("Fairfield") area is kinda up and had a double oval with spur in a 4 X 8 area. I will then have a track area leading along the Mississippi to (part) of the QCA and from there along the Mississippi again up to Clinton. I'm thinking of having the Iowa country-side and river parts as modules (as per the NMRA standards and plan on their web site). The QCA region (Davenport. Was going to be Bettendorf before I moved!) and Clinton will be a more standard table-like frame for a foam bed like Fairfield.
To do this, I only have a 11 X 12 downstairs bedroom (with a 3.5 X 5.5 closet extension in one corner. Or a bit over 150 sq ft.
Nowhere as much area as you are planning on!
I plan on running 6 main trains:
A BN coal for the QCA area, a UP intermodal thru the QCA down from Clinton, a RI "Clinton area" that serves ADM, Clinton Corn, and DuPont in that area, a RI "QCA" train serving John Deere, Case, Moline Paint and other QCA clients, and a QC Rocket that will meet the AMTRAK Zephyr at Fairfield.
So for this plan, I think the Zephyr gives me just what I need to operate. But this is far less area than you are planning on, so a bigger DCC system might be needed for your layout.
But that will depend on exactly how many trains are running at a given time, how many dummies you have and/or if you do Gary's trick of giving more than one loco in a MU consist the same address and if you can release addresses between train runs.
You could start with a Z and then expand (although it is more expensive to do it this way in the long run, I think).
Or go directly to the Super Chief (or Lenz equilivent).
Either way, or either system, DCC is fun!
BTW Gary - I checked - the Z can release loco addresses as you thought. Thanks again for the info!
- George