Chris,
I work with Delta and live in Europe. I will give you some pointers tomorrow when I have more time...but reply to this and let me know where your are flying FROM and what dates you are looking at. I can check loads and help you make a more educated decision. Remember that the employee or spouse or child are the only ones who can redeem the buddy pass certificate for a ticket...so if you have the certificate, delta will not let you redeem it without the employee/family member present.