We got 1 in 12 go free, you just pay the taxes. We've also been upgraded to the Honeymoon Suite (subject to availability, so we'll see if it actually happens) and 'Elite' status on the flight - I think that means extra baggage, priority boarding, etc.
We're also trying to get our entire group upgraded to preferred service at the resort.
I originally dealt with DW.com, but decided to go with a local TA instead because I heard they are not TICO insured (Ontario travel insurance)...