I love Ava (it's my 6 year old niece's name) but Ava Grace has to be the most common combination I've heard. I know 4 people who have chosen this combination in the past year. If there's a meaning behind it great, if not I would recommend a different middle name.
I love Lillian. If my sister's name wasn't Jillian, it would be our top choice. I am not crazy about Belle though. I personally like a longer mn with Lillian. Something like Lillian Elizabeth.
Re: Girl name?