Based on your description and only having 2-3 engines, I assume that both loops will be electrically connected and you are just looking for advice on how to best power both loops.
I would skip getting two transformers like the CW-80 and focus on getting one more powerful supply like the GW-180 or a brick. My preference would be to use a 12 port MTH or similar terminal block like the one shown below (you can get similar ones on the big A or the bay for a little less money).
You would simply connect the transformer or brick output to the terminal block red and black inputs and then you have twelve outputs to connect to the track (6 per loop if they are about the same length).
Buy a roll of 14-16 gauge stranded, paired copper wire. On the terminal block end, just put small spade crimp-type connectors on the wires and screw to the output port. On a sheet of paper or in your head, divide each loop into approximately 6 equal "blocks" of track. Connect the wires coming from each of the 12 output ports of the terminal block to a piece of Fastrack ("FT") about in the center of each of your blocks. Since you will have a small yard, you would include that as one of your "blocks" on whichever loop it is connected to. You can adjust how many connections ("drops") you need for each loop. If you think you might need more than 12 power drops, you can also find and use a 20 or 24 output port terminal block.
FT has metal + and - tab connectors underneath most individual pieces of track (center tab + and outside rail tab -). Buy a package of the connectors shown below and connect them to the ends of the wires that will connect to the underside tabs of the FT track pieces and drill a hole up from underneath the plywood where the tabs are located on each piece of FT that you will be connecting to and thread the two wires up through the hole and connect to the FT tabs (the connectors "slip" over the tabs).
When you're done you will have 6 power drops to each loop, which should be enough so that there is no voltage drop anywhere along each loop. In addition, none of the wiring will be visible.
If you have a larger budget, I would recommend getting an MTH Z-4000 transformer where you can connect each handle (one for each of your loops) to a separate 12 port terminal block and then as many power drops out as you need for each loop and the yard. The Z-4000 also has separate 10v and 14v accessory outputs which you can also connect to separate 12 port terminal blocks and then out to your accessories. I like it because most all your power needs are consolidated in one unit.
Pretty easy to wire up and you're good to go.
