Thanks thats really helpful.
First I entered this;
$credRootUser = Get-Credential -Credential root
So i could cache the credential and then used your suggestion above.
Import-Csv c:\esxi.csv -UseCulture | %{Connect-VIServer -Credential $credRootUser -Server $_.Address}
Now all i have to do is figure out how to export a single CSV with the datastore sizes and hostname line by line.