Well I went to AWS Re-Invent for my speaking session, and I must say that was an adventure. I have been to large conventions before, like VMworld, Dell , etc. This by far was the largest.
I am not sure how many hotels were involved, seemed like every hotel on the strip had something for Re-Invent, from sessions, meals, presentations, or dinning specials for attendee's. I believe there was an estimated 60,000 people in attendance, every session was full that I tried to attend so I spent time on waiting lists, or in line hoping for a spot.
As far as the session I was speaking at, there were allot of seats open, i invited everyone I know or met to attend the session. All in all we got about 25-30 people to attend the session on Zerto. And it let to some good discussions around VM's and protecting them in AWS.
I also tested for AWS Sysops certification, I first took a boot camp the day before and paid additional $225 for, which in my opinion was not worth the money. It did not teach more that I feel i could have gotten offline. The test was challenging not a typical certification teat I have taken before, very in depth and really need to understand how AWS works. Needless to say I did not pass the test I came close I believe within about 5 questions... I am going to study more and take the test again in the next few month's...
I dont think I will go back to Re-Invent unless asked again, it was to many people and could not get into any sessions I wanted to, I will stick o smaller conferences  :-)..