Nice progress man, and i glad u try to use my recommendation (for numbering i think).
The C part seems good and has a potency for improving. The C part also seems like a main large city/ maybe a capital city, and there are the other areas surrounding that main part. Personally, I really like your thumbnail now.
On the other side, the B part also interesting, has a strength silhouette, and also has a sense of depth. However, personally it looks too narrow, and it more matches for a key frame purpose than a world or city concept purposes. If I were you, i would enlarge my canvas and make it wider.
Here, I just giving you my personal opinion, not to ask u to follow my instruction.
Perhaps, the other members have different thinks, so let them to give you feedback too
Keep it up man, 
