Maybe it was brought up before, but here's adorable Mew personification I found on web. While the skirt should be edited a bit, this picture is just lovely. For me it has that playful vibe along with a bit of mystical feel. IMHO something like this may fit moe Mew more then current magical girl design. Just my own opinion.
http://kadajstrife0.deviantart.com/art/moemon-mew-201576670