Alice or Arthur would be lovely, but at the same time I want to use those names so i'm hoping they don't!
I think Matilda or Adelaide is a pretty choice and a nice diplomatic nod to Australia, Alexandra would also be great. I'd quite like to see an Edward who goes by Ned or Teddy.
I'm not sure how set in stone royal naming protocol is, I think probably most of it is just unwritten rules of convention, it's so boring to have to just keep recycling names, the original name bearers certainly didn't - they chose the names purely because they liked them, which is how it should be I think.
Alexandra Amelia Caroline Diana
Caroline Diana Elizabeth Jane
Margaret Louisa Carol Elizabeth
Elizabeth Victoria Louise Diana
Sophia Catherine Elizabeth Diana
Matilda Caroline Diana Margaret
I would guess that they either go with a "traditional" royal name, with a few "non-traditional" middles (like Diana, Carol...), a traditional royal name with a funky/spunky nickname (ala William aka Wills), or a modern first name with traditional middles (like Mabel Elizabeth Diana Margaret).
I think a Princess Alexandra, nn. Allie, Lexie, or Sandy would be adorable!
I also think that Princess Diana will be honored, as well as Kate's family (whether that be her mother's name or another family name on her side).
Something classic that fits with family names. I don't know much about them or family names enough to pick two (boy and girl).
This is an interesting proposition! Traditional or classic with a modern twist? I couldn't decide, so I chose to pick two name combinations, just because I can!
Traditional choice - Alexandra Eleanor Margaret Diana - (love the idea of the nn Lexi/Lexa, Eleanor and Margaret are classically elegant, and Diana had to be included because she is such an important part of William's life).
Classic with modern twist - Arabella Charlotte Spencer Jubilee (Can't get much more princess-sounding than Arabella! Charlotte is traditional modern elegance, Spencer is a twist on Diana (her maiden name) and Jubilee is a nod to the Queen, as it was her Diamond Jubilee celebration in 2013). Absolutely no chance of even being close with this one, but that's the best part of being able to have free reign with suggestions!
Whatever William and Catherine choose, it will be the most anticipated name choice of the year!
I would name her Georgina.
If I could choose a girl's name for William and Catherine:
Caroline Elizabeth Diana Catherine.
I'm rooting for a Matilda or Eleanor for a girl, Arthur for a boy.
I imagine Diana or Carol (or Caroline) will be honoraries in the middle for a girl, Elizabeth too, perhaps. Phillip or Charles for a boy. I expect to see a George in there too.
Matilda Diana Elizabeth Anne
Eleanor Diana Caroline Anne
Arthur George Charles Phillip (though probably not, since all those names are in Prince Charles's name, just in a different order)
I am 100% certain if it's a girl that Elizabeth will be in there as a middle name. I think there is a good chance of the first name being Victoria as it's not currently popular in the UK, is a classic royal name and if the baby is a girl and will be Queen, then Victoria harks back to a golden age of female monarchy. Catherine may well be a middle. My best guess is Victoria Elizabeth Catherine Diana (they tend to have a lot of names!)
For a boy I would be fairly confident that Charles will be in there, also possibly William. George is a really good guess for a first but George VI was really Albert which would be quite on trend over here, so MAYBE there'll be a Prince Albert (although that would nix Victoria for the future!). George Phillip Charles William.... But maybe Albert :-)