The fact that I am a travel agent aside, I would always use a travel agent for larger packages. This is your wedding! Not just a $200 airline ticket!
A travel agent helps you coordinate your plans, and you always have one person to work with. It is their job to deal with all the different providers and to make sense of it for you.
I would certainly look for a Disney Specialist (Graduate of the College of Disney Knowledge) and make sure they are familiar with the wedding packages. This is not a grey area where the agent can just say - "Oh sure - I've booked Las Vegas weddings...Disney won't be any different!" The agent NEEDS to know Disney!
I have been doing WDW and DL wedding packages for years - If you would like more info from me, PM me. I don't want to be accused of soliciting business here...but I do like to share my knowledge.
Natasha - depending on what type of package you are intersted in it may actually be cheaper to book it on your own. I would suggest looking at www.mousesavers.com before you book with a travel agent as Mary's website has tons of discount information and break downs between package and on your own.
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