I relate to almost everything that has been mentioned above.
I relate to what Paul said because I am likely only to use the basic features of DCS for the foreseeable future, and I know I'll be making operator's mistakes. To avoid them, every time I start up an engine using the DCS remote, I turn to the DCS Operator's Manual and follow the step by step process therein.
Barry's book, mentioned by Raising4daughters, is indispensable; I regard it as my DCS bible. And, I also am not planning any DCS accessory or switch control.
At this point, having installed the TIU and running DCS for only 2 weeks, I am content with the basic DCS features.
I have 2 Z4000 transformers and the Z4000 Receiver to use the Z4KTracks, but I have not connected the Receiver yet. I got the Receiver because MTH may be closing its business soon, and I want the option, down the road, to run my Postwar and PS1 engines using the DCS remote.
I also recently acquired the necessary equipment to run TMCC and Legacy engines using the DCS remote, but have not hooked it up yet. Again, I want the option to do so, down the road.