Royal Weddings, edited by Friederike Haedecke and Julia Melchior, takes a look at the pageantry of royal weddings in such countries as Sweden, Japan, and Spain. The text is in English and German.
The book includes 125 color and 57 black-and-white illustrations, including wedding invitations and little-known photos capturing private moments. It also has a very nice cover, which unfortunately isn't being shown on Amazon.com yet, but Friederike Haedecke sent it to me so Royalty.nu visitors could see it. Here it is:
Thank you to Friederike for this image!
2013 UPDATE: The new edition of this book uses a new cover image, but the old version with the Diana cover is currently still available at Amazon.