App Engine, for everything.
I've been using Unix for 3 decades and at this point I see any time spent administering or setting up servers as time wasted when I could be adding value to the product. App engine gives me all the administration and half of the scalability solution I need, so I spend my time adding value.
I am amazed that so many of you have root. I'm guessing it comes because you value the control, and don't mind spending time on system administration?