I absolutely adore the name
Ivy!! It's short and spunky so I think a longer, classic middle name would work wonderfully.
Ivy Cecilia has a nice flow even if I'm not a fan of
Cecilia.
I think I prefer
Ivy because I never hear it whereas
Rose I hear a lot. As a middle name, of course, but it seems like in recent works of historical fiction the heroine is always called either
Elizabeth or
Rose. So I vote for
Ivy!