Go ahead and eliminate the never-used tub.

How big is your current shower? How deep is your closet?

One option. The original space allocated for your toilet can be used in your closet.

Current shower is about 35” x 59”

Current tub is approx 4’ x 6’5”

We have two very large master bedroom

closets so I have no need to move or take from the toilet to add to the closet.

I was thinking of moving the new shower to where the tub is, moving the sinks/vanity to the wall where the shower is, but then I would have that big area of dead space where the sinks are now. I thought about adding a linen closet in that corner but I dont want a linen closet that big and there would still be dead space.

If we kept the shower where it is, we could make it longer but not wider due to the window.

I should clarify, the sink, shower, tub area is 10’x13’ (That doesnt include the toilet closet which I don't need to do anything with.)