Booking with Disney is always a good choice if you are like me and feel like you need to have control over the details.
If you would like someone else to work on the details required then an agency is a great option. I have not used Dreams Unlimited, but I know others here have and will be willing to share your experiences. If you do use an agency, still to someone you know or someone recommended. Using a big name like Carlson Travel or American Express Travel should take some of the uncertainty out of it for you as well.