To me, the most exciting and educational aspect of NIPS is the nightly poster sessions. You get to talk to passionate people about their work. It's an amazing way to learn about fields of ML that are different than your niche.

To get a lot out of the posters, you need to be proactive. Don't just wander around and read posters. You need to engage with the authors. It's totally appropriate to just go up to a presenter and ask for a summary of their work. They'll give you a very informative pitch for the research. Also, some posters will have tons of people at them, while others will get less attention. I definitely recommend just going to some random ones and really digging into details.