KeithT - the HP Indigos can use sRGB as a default profile so you can pretty much throw anything at it and get a good result - even though the Blurb profile is CMYK.
wavemachine - would you like me to make your life a lot easier for wedding books? Go
here and try their software. Once you have it installed, select a book, the wedding pics and hit 'autoflow' then choose 'picture order'. And within a minute (or less) you should have a completed book that will have used all images once in the order they were taken with no blank picture boxes or pages. You can then use page styles and masks from the bottom pane to drag and drop and get the look you want. And they use 'lay flat' pages and print using HP Indigos (they're a client of mine!).
All the decent softwares will render the final book as a PDF and then upload it - makes the resulting file a few MB instead of a few hundred MB with all the images.