I did this a few times, you need to call Delta to book it and they always book the low awards, they told me once they dont have the three award tiers on partners.
Not sure what they charge from ATL, but i paid 40K miles for Berlin-SVO-TAS and back.
You need to find i think X availability for coach and O for business.
ULN shoul be the same mileage. Service was great.