power supplies to track

This is about power for your train and accessories not about the control system.  72W is a marginal power source for an expanding layout.  I would at least phase 2 for the two loops.  The siding can be on one of them.  G

You don't need a block system to run LionChief locos, but I think it's a good idea to have one. As you add accessories you will probably need more power than the 72 watt supply can deliver. 

You can run two trains, maybe three if no lighted cars, etc.  with 72 watts, but that leaves you with nothing for accessories and building lights, etc. which on some layouts can take 80 watts right there..  You will want more power eventually.  

An important point to remember is that you may want to run some conventional locos or Legacy/DCS locos in conventional mode, and so having an ability to set the voltage on at least one loop to operate a conventional loco is worth having.  

My loops are 16 ft long by 6ft wide on one end and 5 ft on the other side. So, going with one power supply on each loop should do it?

Absolutely, the length of track doesn't matter as long as proper sized wire and drops are used.  How much power is needed depends on the load (engine, accessories, lighted cars, etc...) 

With a loop that big you can get more than one engine on it, most folks would want a 180W 10A source for that.  G

Please take note that the output of the LionChief power supply is DC volts. The LionChief engines will run ok on either DC or AC track power.

Other engines and accessories may be designed for AC. Keep that in mind when you are considering adding more features to your layout.

Is anyone aware of the purpose/reason for using DC power supplies in LionChief sets?

The reason for asking is that we had a customer purchase a set and was planning on using an MRC power supply to run the train and the employee assisting the customer advised against and AC power supply because the wall wort was DC.  I was under the impression that these trains will run just as well on AC so before I put my foot in my mouth I thought I'd ask.

Nevermind this, I found the answer here.  Thanks anyway!

I was told lionchief trains can run on ac or dc power supplies.

According to the Lionel catalogue both LionChief and LionChief Plus can run on either AC or DC.

Thanks Joe. That's what I was told, too.

Correct, we have run both types on the Lionel PH-180 brick at Henning's.

Can I run a 180 PH power supply direct to the track for the Lion Chiefs or does it have to be through a power master first?

LC is meant to run on 18V just like Command engines.  So you do not need the power master.  Just a PH.  It just replaces the Wal wart or other DC transformer.  G