Hate to say it, but parent is almost completely correct.
There are some bennies to being on-site (hands-on labs with an expert on hand), but otherwise most conferences are just a big marketing push with a lot of hanger-on companies and startups vying for your attention on the main floor.
It wouldn't be so bad if the exhibitors had actual experts on hand to answer the tough questions w/o resorting to market-speak, but most of them don't, and are too busy evangelizing. If I wanted to get pounded with marketing-speak, I'd invite VARs to stop by at my office for that. If I want swag or bennies, there are plenty of local ones that local VARs are happy to give/throw (e.g. watching a Trailblazers game from a box seat while the VAR spends halftime talking to you about his product lines).
The last conference I went to was VMWorld in 1999, which had the hands-on labs and an opportunity to speak with the actual VMWare developers in an intimate setting about upcoming bits and existing problems (albeit the latter was restricted to certain big buyers/partners), but otherwise it seemed to be nothing more than a means to work over VPN interspersed with advertisement on-site, and more marketing disguised as after-hours drinking parties.
Seriously... They were fun as hell, and you used to learn a lot in the process, but the days of COMDEX and NetWorld are dead; you can thank the Internet for that.
Now classes or boot-camps? Different story, and still well worth going to depending on the technology and the depth offered. Conferences? Not so much.