AWS Re:Invent is supposed to be a great conference. I have thus far been unable to attend, but the videos of the presentations are posted online with about a day’s lag. So, like most conferences, you really should be networking and meeting people face to face rather than attending the presentations.
Here’s the AWS Youtube channel where you can watch all the videos, or just sample them.
I’ve found the talks to be of varying quality. Some just rehash the docs, but others, especially the deep dives, discuss interesting aspects of the AWS infrastructure that I haven’t found to be documented anywhere (here’s a great talk about Elastic Block Storage from 2016). The talks by real customers also give a great viewpoint into how AWS’s offerings are actually implemented to provide business value (here’s a great talk from 2016 about using Amazon Machine Learning to predict real estate transactions).
It’s a sprawling conference, well suited to AWS’s sprawling offering, and I bet no matter what your interest, you will be able to find a video worth watching.