I like Anne Marie. Rosalie is your DD's name, right? I think I saw that in another thread when I was searching for posts with Rosalia (we are naming DD #2 Rosalia). Some people like name their children with similar names... I know someone who has a Gianna and a Julianna because they wanted similar sounding names. I think Anne Marie is pretty and if you don't mind the similar 'ee' sound then go for it .
AnneMarie and Rosalie do sound very similar but if you like it then thats ok.
to make it sound less 'plain' what about AnnaMaria?