I've attended YASC 6 years in a row in the past - LOVED, LOVED, LOVED it. The conference is usually in September or October. Sign up EARLY - as soon as they make the announcement, you should sign up. It usually sells out in about a month. (At least it did when I used to go to it.) I think they usually make the announcement in May.
EXTREMELY helpful - they have beginning sessions, intermediate sessions and advanced sessions. Additionally, most times, you get to meet your support rep - it's always nice to meet the person who's helping you the most. AND, you get to talk directly to the instructors, engineers, influencer's, VP's, etc. All the years I attended, I even met with and talked to Anant Yardi. Very down to earth, driven, extremely intelligent, motivational man. LOVE him! It is seldom that I meet the founders/owners or large companies and feel this way.
There are a TON of companies there, so you have the opportunity to meet other like-companies and share stories and experiences.
And, you can find great consultants there - they are always milling about. Ask the other attendees who they use, and then chat up those consultants.
Lastly, it's in Santa Barbara (at least it was the 6 years I attended), and its perfect weather all the time. If you go a day early, you can attend the farmer's market and have your pick of the sweetest, freshest, locally grown fruit. If you stay a couple days after the conference, Santa Barbara is a beautiful city to explore, and very tourist friendly.
Hope that helps!
-Daisy