Can girls use だよね in everyday conversations?
Certainly yes, girls can use だよね, but it may leave a slightly tomboyish impression. The first Japanese hip-hop song which sold one million records was called DA.YO.NE and is mainly performed by a girl.
On the other hand, boys can use だよね, too, but IMO it's mainly used by boys who always stick to 僕 instead of 俺 as a first-person pronoun. (I mean, it sounds a bit gentle or "pretty.")
I can confirm that women in their 20s and 30s say だよね with high frequency in Tokyo. Personalities in the range of very feminine to slightly boyish in behavior. That particular phrase seems fairly gender-neutral to me, I'd like to mention.