I did frosted glass doors in my bathroom. I love the look they give!

all sorts of ideas. budget would come into play, natch.

To update the area,(if you want) the arched window transom would probably have to be redone to a rectangular shape. Ditto for the glass in the doors. no arches.

I wouldn't make a closet into a feature by adding a dramatic door. I'd paint it gray to match the wall. Door trim too. I've never seen a door with a baseboard nailed to it unless it was one of those hidden doors.

I would not add stone to the fireplace wall. That will draw attention. Your new railing makes me think you desire a clean more modern look. I'd paint the brick and possibly the shelves and mantle.

Get a very simple firescreen as well.

When you get around to the fireplace, there are non-acid, non-toxic products to change masonry color. Dyebrick is a stain for use on brick and mortar. They have a product called LimeLike to lighten dark brick so that a lighter color can be applied over that. Since this is not a paint it preserves the texture of the brick. They have an extensive Gallery of projects to view.