How do I Avoid Very Long Horizontal Signal Path "Snakes" in a Schematic?
The question is still open for suggestions. Meanwhile, I've spent some time attempting to rearrange the diagram, and I identified three modifications and the schematic is significantly better now.

1. Increase the Width of the Blocks

Do not put wires directly to the points of connection on the symbol. Use some vertical wires to create additional widths. 

This is a snake.



But this is better.



Similarly, larger versions of components symbols (resistors, capacitors) should be used to fill the gaps, so the dense parts and sparse parts of the diagram can have the same width. 

2. Put "Snake Like" blocks vertically.

I've finished the RF parts of the circuit, still a "snake". But when you arrange two "snakes" vertically, narrow "snakes" becomes rectangular.



3. Put Input and Output At the Same Side

Although the rule-of-thumb is routing all signal flow from left-to-right, but putting both the input and output port at the same side avoid irregular shape of the drawing.

Final result



I think It's not the best possible schematic. But now the readability of the drawing is greatly improved. There may still be rooms of improvements. Any comment?

4. Move the Output to the Right

Following the comments, I moved the output to the right to make sure that the signal always flow from left to right, meanwhile I've put the LDO circuit at the left side to balance the schematics. Not too bad.