Many of the older safes are just gorgeous - IF you see one that has had the original painting restored.
There's a very good antique-safe dealer near Dallas who's got an enormous Mosler right now - the only place I could fit it is in my living room or den, but it'd be an unusual ornament!
I like a safe that looks like a huge industrial appliance (which it is), but also has some nice decoration - sort of the "decorated locomotive" look. What I'm getting at is that many modern safes already have lots of their structural elements concealed or understated, and that's really the biggest choice in appearance.