OK, let's start with the purpose of your yards. Are you just looking for places to store locos and cars? Or, do you really intend to break-up trains that arrive and make-up trains to depart? Second, what's the over-all operating scheme for your railroad? If you haven't figured that out yet, it is something to be considered.
As drafted, your plan looks like a large oval on an "island" with the island center filled with yards. Have you considered an around the walls layout with each (or most parts) being less than 3 feet wide? Then you could create two separate yards (maybe on each side of the room) and operate cars from one yard to another. Have you considered engine facilities or storage? Have you considered how to turn an engine around (reverse) so it can travel in the opposite direction?
Finally, what are the impediments in the "room" that will affect the location of your layout and where are they on your drawings? Consider electrical, plumbing, heating, doors, windows and anything else that you just can't move but may need access. And remember, the best advice I've heard is that the name of the game is NOT "Fill that Space." Translated, that means don't overuse track.
Chuck
Oh, and just for info, yard run-arounds are normally within the yard limits, not out on the main line.