I've used PowerCLI to do this type of thing for disk performance testing. It works great, especially with version 5.1 R2.
Give this a shot.
$numVapp=100
$vAppBaseName="ExampleVappCreation-"
$vAppCopyFrom = Get-CIVApp -Name "Your vApp or vApp Template"
for ($i=1; $i -le $numVapp; $i++)
{New-CIVApp -Name ($vAppBaseName + $i) -VApp $vAppCopyFrom}