If you search there are a few threads on this - I know the ones at Downtown Disney do. If your going with a WDW hotel/park restaurant they dont usually have private dining areas but from what I have read they will try and and sit you in a privateish area - due to the size of your table also! Also the restaurants want you to take an early or late seating.
Some brides book their meals directly through WDW but I have seen Escape brides planners book them .
Were looking at the Wave for ours and I know they can partition off parts of the restaurant for private use so I was going ask about it during our trip in October.