It depends on which building you pick for concierge. The GF has two locations. One is in SugarLoaf, which will give you views of the garden or marina. Unfortunately, due to the way the building is situated on the property, it's unlikely that you would get a castle view here. The other location for concierge is in the main building. Those views include lagoon, garden and marina (with a castle view). You'll pay the same price (within that building) for any standard concierge room. Beyond that, you make your request with the IPO staff for a particular view. We've had rooms in both the concierge buildings. My favorite view was from 4404 which is marina in the main building. We had a perfect view of the castle and could even watch it changing colors in bed.
There are actually 3 lodge tower rooms in the SugarLoaf building. They are currently the same price as the standard concierge rooms there and like the view, are available by request. Just an FYI though that all lodge tower rooms have a garden view and those located on the top floors of the buildings don't have a balcony.