WMWare workstation provides a command line utility, called vmrun, to control the guest machines, they are especially useful if GUI is not required.

For example, start a guest instance with following command:

vmrun -T ws start /path/to/instance.vmx nogui

You can check how many guest instance are running:

rmrun list

For more information, just hit vmrun on terminal or refer to Using vmrun to control Vitual Machines.