if you are going to tile the backsplash above the vanity, tile behind the toilet too.

I wouldn't do any more than a backsplash over the sink. The fixtures in this room aren't positioned so as to make that wall a good feature wall IMO. If you do decide to do more than a backsplash, I would do it to 48" as you said, and wrap it around to the tub surround. That's the way bathrooms were tiled decades ago. Once you put a mirror over the sink no one would really notice tile behind it anyway. Is this bath seldom used, or frequently used by yourself or children? If it's seldom used I would keep it simple, not unlike the way it is now. Less tile means it is easier to change the look with paint down the road.

Thanks. I agree. That’s my plan