Some ideas...
Antiqued finish on the mirror:
Todd Romano
Jan Showers
Maybe some rosettes on the tiles to break it up?
Adding moulding makes the mirror look more expensive, less DIY.
JK Capri Hotel
Layering with bookshelves is one of my favorite looks:
House Beautiful
I really love the idea of hanging art on the mirror.
Elle Decor
Want another way to achieve the 'wall of mirror' look without the commitment? Add mirror to your interior doors.
Christina Murphy
Susan Jones