Many years ago you would attend and get some good knowledge, not now nor has that been true for say the past 20+ years. I would say 99+% of the "classes" are about how this Product will make your life better and you get Mom and Apple Pie too.
About 15 years ago, I told my manager that I will no longer go to these and maybe you should send the new young hires to them. Why, most of them will feel good for being picked and are a bit too young to know how much of a waste most of these conferences are :) Plus the young people will get to see competitors of the products we bought, getting a better idea on how to do things.
The only other people that these would be good for are marketing people.