It's....
Well, it's INCREDIBLE. Absolutely amazing. Stunning. Life-changing.
That might sound dramatic, but they really have affected my life in big ways. I've met some amazing people....learned information that changed how I run my sites entirely.....got products that altered what I do on a day-to-day basis.
That being said, it's not like that for everyone. Some people walk away disappointed and not "getting" it. It's what you make of the experience, though. If you just sit in your hotel room the whole time or spend the whole weekend focused on getting 'swag', then you're going to have an entirely different experience than I do.
Yeah, I'm expected to do academic conferences in my program. And most people do the hotel room and swag route and then come home complaining about it not being worth the money, the headache of travel, etc.
As with everything, it's what you make of it. Glad to hear your BlogHer experience was life-changing!!
The other thing I've heard with conferences is it's 1) a networking tool and 2) a friend making tool. So I guess I would say to keep those things in mind if you decide to attend a conference.