If you prefer keyboard shortcuts, the Windows key will open the Start Screen, the same as it has opened the Start Menu since I first found it on the keyboard of a new Win95 machine. The CTRL-ESC combo works too.

Don't get me wrong, I'm with you on the uselessness of live tiles in a working environment. For example, the Email tile ties to a Windows Live login, basically a Hotmail account, not my Exchange server account. I've got 75 users in my corporate environment. Am I supposed to give them all Hotmail accounts? That's just stupid. In experimenting with different setups, I find the best option is to remove all the live tiles, they're useless.