I just used Orbitz for the first time for a VERY last minute Disney trip. I used the code SAYYAY and received an additional 15% off the room so the Orbitz rate was way cheaper than any I found on the Disney site.
One downfall is that you do have to pay for the entire trip at once, not just a deposit like you do at Disney. I haven't had to cancel so I can't give any input on that.
You are going to have to contact Orbitz after you've booked to get the 10 digit Disney confirmation number to link your reservation to your
MDE account to make your FP+ selections. Orbitz will give you a hotel confirmation number and booking number but neither are the actual Disney confirmation number. I don't know what the average wait time is for that number but it took almost a week to get mine - Orbitz said it was a delay on the Disney end. No big deal though - I was able to link the reservation with no trouble. I used Live Chat to talk to an Orbitz agent. They were very helpful. Just be sure to specifically ask for the 10 digit Disney reservation number. I will definitely use Orbitz again to book my next Disney trip =)