Power and control suggestions needed on my layout

You can use one remote for both TIU.   The WIU only connect to one TIU.   I have 2 TIUs and use  2 WIUs.  I do use my remote a lot of the time.   I used MTH Z4000 for TIUs vs bricks since this is what I had.   You can the bricks or add the ZW.  It is your preference.   I use the z4000 to run conventional on my tracks as well.   I use 6 of the TIU channels 4 for main lines and 2 for large yards. 

My question is why do you need two TIU's for a layout this size?  I have a 12 x 24 layout with a 15 foot 10-track yard extension, and it runs fine using one TIU.  I'd consider re-thinking the need for two TIU's.

Thanks for the replies.  I'm just asking if I needed the second TIU because it came with the WIU. I was wondering if I can control trains with the handheld and WIFI at the same time using one TIU. If I can run them with one and use less bricks that's great. So I guess it's overkill.

Gunrunner,

Do I have to add the handheld to the newer TIU?

Sure, you can connect multiple devices to the WIU, and at the same time, connect multiple remotes to the TIU.  I've had two phones and three remotes all connected to my single TIU.  If you look at the panel, the WIU is on the lower left of my previous picture.  IMO, unless you have a layout that needs the extra channels, a second TIU brings nothing to the party, but it can sure confuse the works.