Wait, on second thoughts, I'm not sure if it would be very suitable for my castle to be spawn, although it would be cool, I don't want it filled with signs and stuff as that would make it look untidy.
If you are going to use it as a spawn, can i suggest having all of the notices OUTSIDE the castle, but placing them along the path from the castle and having the path restricted so that people are forced to read the signs, just like in the old world where we had the floating spawn with a path with signs along it (the world that got deleted when the server first crashed).