I love them both. Tough decision, but I would probably choose Juliette(although I prefer the Juliet spelling).
As for middle names I second Felicity Catherine and Felicity Charlotte.
I also love-
Felicity - lovely meaning and although I also love Juliet/ette it still rings to much of the character . (although I do love the nn etta)
love prior suggestions of
I also like
Felicity Joyce (although these two may have too similar meanings)
I'd go with Juliette.
Felicity is my favourite, but really you can't really go wrong with either