I would start by aging a beautiful oriental rug with warm reds in front of the tub and go from there

sorry, not aging but laying

A spa blue would be beautiful. Add a runner with blues, beiges. Paint walls soft grayish blue. Accent with silver.

The dark surrounds/frames on those mirrors/medicine cabinets above the sinks: can you make them white? And do the same to anything else that's similarly dark? That wd sort of clear yr slate. Agree about the rug. -- doesn't have to be oriental, but something that agrees with walls while adding some brighter colors, then pick up the brighter colors with other touches. What strikes me is that this room is full of aggressive-looking angles right now -- you could soften that with long, graceful lightweight/sheer drapery fabric at the window and some green plants.

The tile floors and countertops are not so bad, take heart! There's a nice article currently featured on this website about livening up beige, several options using different extra colors -- blues and greens cd be nice for the bath. If you truly hate the color of the walls, it doesn't look like it wd be a big deal to paint from yr pix -- one gallon & three hours!

first things first, change the light fixtures. and take out the builders series .....every new construction home......annoying they cheap out on it every time.the out lets appear to be centered over the sink rather than the mirror.....change the mirrors to fit each sink area. then use the new wall space to add color.
get something with less of a back plate, and add a rug, some colorful towels and some glass bottles. what is that opening on the far wall?

the door on the end leads to the closet

This is how the counter looks up close.

all different tones of brown

I think a white bench in front of the tub, white rug (spa like or even a white shag) would look nice. A touch of aqua blue if you like. Or, just lighten and freshen with bright white.

where is all the lighting that closet looks like a blck hole, tell me there is good light in there. is there lighting over the tub?

No lighting over the tub it's a glass window