I've been coming to TechEd for many years. Proximity to the convention center is not so important, unless you are able to get in at the center itself. Otherwise, the bus runs back and forth all day and hasn't been a problem. I'm at the DoubleTree because it is close enough to other things. There's a casino there, aquarium, etc. After hours of brain cramming, it is good to have some fun before you need to return to the room and work all night.