One of my favorites is the "Open Tab" behavior preference. If you go to "Behaviors" in Preferences, you can set it to go to a specific tab whenever a run starts. You can name the tab, something like "Debug" and Xcode4 will create it for you if it doesn't exist, and take you there when you start debugging. You can configure this tab just how you like it for debugging sessions, and it will stick that way after you close it, so whenever you do a run Xcode4 will be set up just how you want it, in a separate tab. You can even tear this tab off to a separate window, in which case Xcode4 will open a new specially configured "Debug" window each time you start a run! This feature is great because it keeps your regular code editing tab or window uncluttered with the log and debugger panes. Simply close the "Debug" window when you're done running and you can be back to your clean screen of code.
