Wow, I love all of those names...I mean it...that's a bit scary actually...anyway, I think maybe since you have used names like William, Clarissa & Louise, which aren't that, 'contemporary' (though i love than!) and also you've also used names like Alden and Rohan (which are very unique) and also, Mason is pretty new, but uncommon, so i think a unique, uncommonish name would be good.
Sorry, ignore my messed up ways of reasoning.
Regan Maria (adds to the oldish/unique/uncommon theme, sorry ignore these comments lol)
Megan Rose (Way to common -.-)
Janie Gabrielle (Jay-nee)
Farren Elise (Okay, i might have gone onto some ridiculous suggestions)
I hope you liked my suggestions, though i feel like they haven't done that job. oh well :) Congradulations and Good Luck!
Hope i helped, didn't offend and made you say AHHH now there are some WEIRD names :P