Very nice layout design.
I am building a similar size layout with Fastrack and the same bridge. The wiring design is very similar also. I have two loops powered with a 180w Lionel brick for each. I installed both DCS and TMCC. The TMCC will eventually be replaced with a new Base 3 when shipped. I used the same power blocks you have, one for each loop and wired it in the star pattern that was recommended in Berry's DCS book. The wire I used was 16g solid copper black and red insulated speaker wire. Made it easier to run the wires since they're joined together. I have been satisfied with the results so far. Plenty of power.
To minimize flickering and future problems, I did take the time to practice some and solder a 22g jumper wire between most pieces of Fastrack when I installed it. The main reason is my design required me to use many 1 3/8" and 1 3/4" track pieces. They have a history of current issues over time. By soldering a jumper between them I could Guarantee continuity and significantly reduce the number of drops necessary to give consistent power.
I have been very pleased with the results. Passenger cars that used to flicker constantly on my temporary layout have no noticeable flickering now on the new layout, even through the switches and crossing.
