I actually quite like Oaklie for a girl, also, if its a girl you don't have to worry quite as much with the first and middle name matching the last perfectly, chances are she will one day get married and gain a new last name. But you do want a good first middle combo. Both sides of my family are filled with Lynn middle named girls. My sister, husband's sister, mother-in-law and two nieces all with the same middle name.
Our 19 month old sons name is Oakley! We love it so much. I've never been a huge fan of Oakley as a girls name but that's just me.
Other O names are Ophelia, Odette, Odelia, Olina, Olive, Olympia, Opal.... I do think that Octavia is quite a nice name though. Good luck!