I stumbled upon this technical note from VMware on how to install vCenter and the vSphere client silently via the command line. Unfortunately the syntax is pretty convoluted, unlike the SQL 2008 unattended method. The vCenter command line install document can be found here.
Just to give you a flavor of the complexity, here’s a working command to silenty install the vSphere client to a custom directory. This only required one VMware switch…vCenter could require a dozen or more. Needless to say, this is not for the faint of heart. It’s probably quicker and easier to click through the GUI.
start /wait Z:vpxVMware-viclient.exe /q /s /w /L1033 /v” /qr INSTALLDIR=”D:Program Files (x86)VMwareInfrastructure”