Hello,
You can share the sources of the Transistor A & B, this way you will reduce area, minimize the no.of drain regions and also parasitics attached to them. With your current design you are introducing coupling cap between the metals by maintaining the source and drains far apart and also the diffusion cut can be avoided, which in turn can avoid cap's.
You can avoid 4 drain nets and can just have 2 drain nets by adding the 2 drain nets like the gate nets in between the 4 block segments. By this placement you will avoid metal cap coupling and also area & parasitics.
Hope this may serve some of your purpose.
Paramjyothi