I have read "long live the queen" and "the lady in powder blue", I just find the Royal Family secretly being magical and have hundreds of secret agents as "wizards" fascinating. Heck, they don't even have to be magical, just have them be involved and how they'll tackle the ongoing rebellion in the magical world once it was revealed to them is enough for me.

If the royal princes (either of them is good) gets enrolled in Hogwarts and knows about Harry's or the wizarding world's circumstances from there -- and how they will react to an actual "Royal" like the fic called "Prince of Hogwarts".

Edit: Forgot to mention the important part: The main POV/MC should be someone from the royal family. My bad!