I worked at Simpson Thacher full-time (More than a year)
Great place to work, would highly recommend if you like a fast paced and somewhat high stress environment - full benefits (including overtime), offices are newly renovated and they have a great cafeteria.
Definitely be prepared to spend a lot of time in the office - not much of a work/life balance.
I applied online. I interviewed at Simpson Thacher.
The hiring process was as expected. I was interviewed by the partners of the firm and was offered an position a few weeks later. Nothing really stands out.