Hans Camenzind, the 555 designer, devoted most of a chapter in http://designinganalogchips.com/ to the 555; the beginning of chapter 11 tells the story of how it was born, and then he tells you how he'd design it "now" (02005, 17 years ago and 34 years after it originally came out, though I think he published one of the redesigns in 01997), either in bipolar or in CMOS, and, more importantly, why; and some helpful tips on how to debug oscillator designs in simulation.

At first I didn't see this, but Ken linked Camenzind's book in the article footnotes. It's highly regarded and free online.

Shirriff's schematics are a lot nicer-looking than Camenzind's. I don't know what software Camenzind was using to draw his schematics, but despite being well organized and laid out, they are superficially rebarbative, almost as bad as KiCad's. Square dots, bright red transistors contrasting with bright green wires, barbed arrows on transistors, collectors intersecting with emitters at the base (or, randomly, not), active-low overbars that are the wrong length, resistors full of 90-degree angles and only four corners, no line width variation, P-channel MOSFETs with the arrow overlapping a wire-connection dot, MOSFET gates too far from the rest of the MOSFET, text overlapping wires, u for μ, etc. The effect is as if he did every schematic in Comic Sans.