I personally would recommend DU and let them deal with WDW. They will look for discounts and answer all your questions. It's a lot less stressful than dealing directly with WDWT or CRO.
Is this your first trip to Disney World? If it is I would suggest you use Dreams Unlimited. They seem very knowlegeable and many people who like to use travel agents say that they have wonderful service. I began going to DW when I was 21 YO at that time we really didn't need to use a TA. It was just me and a friend of mine. and it was only MK You couldn't get a room aat the Poly unless you planned a year in advance and well who does that t 21. Now that it is the #1 vacation spot it is helpful to have a person who knows and loves DW to help you on your first trip.
I know that I was very hesitant to use a travel agent to set up a WDW vacation for me because I always preferred to do everything myself (I had always booked directly with Disney in the past). But after having been a member of the Dis website for several months, and after having read about other folks' Dreams Unlimited Travel experiences, I took the plunge. Dreams was wonderful to work with, they were able to secure me a few Annual Pass discounts on my resorts, and they even suggested PS reservations for me to consider when I was stumped for a place to dine on New Year's Eve. All in all, thanks to Dreams, I had a glorious and stress-free vacation. I will not hesitate to use Dreams Unlimited Travel for all my future WDW vacation needs. This is all my humble opinion, and others' opinions, as it should be, might vary.