I would not advice calling the Resort directly. When you call you will reach the WDW switchboard, not the resort. Once they find out you have a question about the resort, you will then be transfered to Central Reservations, not the front desk.
What I would do is simply ask the agent to note a special request for a Castle view when you first book the reservation or as soon as possible after you book as there are several Lagoon view rooms and Suites that face the Magic Kingdom. Also be sure to mention that it is your 40th Birthday.
By asking for a general request, you are more likely to get it then asking for a specific room number. If the room number you want is unavailable the resort will not know why you wanted that room and your request would be denied. If you simply ask for a castle view you may be assigned one of a number of rooms with an equally good view of the castle.
I hope this helps! :sohappy:
