Hi Princess of Cupertino!
Yes, Brigitte Hamann's biography of Crown Prince Rudolf is well worth reading, but unfortunately I have no idea as to whether it exists in an English translation, although I think her biography of Empress Elisabeth does.
I agree that both the Crown Prince and Max von Thun was/is extremely charismatic, although I think that the latter is better looking (i.e. more handsome) than the former ever was!!
Cheers,
GREENOWL