In VMware's vCloud Director, when a VM is deployed using the guest customization, you can either supply a password for the administrator user or have vCloud auto-generate a password. The auto-generated passwords are 8 characters long and use upper-case, lower-case, numbers and special characters for example "q#Tv21*a". If the 8 characters is not long enough for you you can increase the character length by changing a field in the database.
In both the Oracle and SQL database there is a field in the CONFIG table called 'AdminPasswordLength', simply change this field to be any number that you would like your passwords to be generated with.
Something like this:
set value = 16 -- required length
where cat = 'settings' and name = 'AdminPasswordLength';
Just do not go over 64 characters as you may get some un-expected results in the OS you are customizing.