Hollie,
I attended last year, as an Ariba "on demand" user and found the value was in talking to existing and new customers a huge amount of feedback and experience that not only provided us with some ideas and ways to improve how we were using the system, but also to find out if we were doing things better than others, a sort of quasi benchmarking. If you look up AribaLive 2012 on youtube, you may find several of the sessions on there and make a decision.