My husband and I each had a favorite girl name that we wanted to use if we had any girls. It worked out really well that... we both had the *same* favorite girl name.
Of course, now that we have four girls, it might have been nice if one of us had had another favorite, as we're running out of ideas!
I have a friend who has three sons. Noah, Joshua, and... Colin. It amuses me, because Colin sort of stands out as being the non-Biblical name.
Of course, I have another friend who has three girls: Madison, Savannah, and Dakota. I teased her that if she has any more, she'll have to have "Cheyenne." She laughed and said she and her husband had joked about the same thing... and even needing to use the same name! (Yes, I know there are other options: Carolina, Georgia, Augusta, etc.)