In our case there is no video or multimedia. Just some accounting application, MS Office and browsers. Average CPU usage over work hours is around 700Mhz per VM which seems quite low since max for 2vCPU desktop would be over 4000Mhz. But still 1 vCPU is not up to the task, to many times CPU spikes to 100% for 5 or 10 seconds which effectively freezes the desktop. In same case a VM with 2vCPUs spikes just to about 60% CPU usage (1 core to 100% and second around 20%) and desktop stays responsive.
So there is a dilemma which option to chose
a) 10 or even 12 core Xeon E5 with relatively low clock around 2,4 or 2,5Ghz and provision VMs with 2vCPU
b) 6 or 8 core with 3,3 Ghz and provision VMs with 1vCPU