The first great thing about TechEd is the buzz. You could spend a little time every month poking around on Microsoft sites, subscribe to their feeds and look at the key blogs. I don't do that and instead rely on the geek version of bush telegraph to alert me of newage that I need to be aware of. This works fine for major stuff, and the killer factor is, it's very low maintenance. At TechEd though, there's a load of people who've been beavering away at Microsoft things for a whole year and are busting to show you. You can spend days reading blogs and feeds and forums and really, it's all words; ten minutes in a TechEd presentation, and you can tell from the seniority of the speaker, the information content and the demo whether something is useful now or over the horizon, irrelevant or cool, forget it or must have.
Azure is a good example of this. I have a blx alarm that automatically goes off every time I hear the phrase "in the cloud", and until last week it has protected me from discovering much about it. I figured I'd better go to an overview since there was so much buzz, and ended up going to a couple more sessions to get the big picture and some practical demonstrations. If MS get the scalability / cost right, and if they make deployment a doddle, and if you can write your app in such a way that it is deployable in or out of the cloud without too much hassle, it could be big.
The second great thing is the random element. It's important to go to the widest selection of sessions that you can, since often the least likely turn out to be the most exciting. You can use the Robotics product to make a cut down version of Windows; that has to be good for something. You can also use it for loosely coupled but high performance applets which must inter-communicate. Virtual Earth, which I had pretty much written off because the Google offering is so good, is actually much better than I realised. There's no excuse now for customers to shy away from GIS functionality in their applications.
Finally, it's a great team builder. There's nothing like being in an away team to clear the air and refocus. It's good to be on the plane home too though. A week's uninterrupted geekery is enough for me.