The question about cost depends on several factors. Is the bathroom on the first or second floor? Whats below it?? Of course where you are makes a difference as well. We added a master bath last year. It was on the second floor, over a office below and there was no plumbing there at all. The plumber had to bring the entire stack up from the basement and then put in toilet, tub, shower and sink and put the vent up through the attic to the roof. The cost was about $5000- which I thought was reasonable. This was just the cost of labor- valves and fixtures were extra. We also had to pay a carpenter to box in the pipes in the room below and repaint of course!!! (One thing always leads to another) We are in the Boston area. You already have plumbing in the area, as well as an air stack through the roof. Remember too that depending on the size and circumstance of your space raising up the floor might make replumbing much less expensive than either putting it into the floor- or under the floor as we did. Good luck

Well it's hard to figure lighting if drawings aren't accurate or noted well, and when plans aren't thought out well enough, but "just adequate," I often hear "it's too difficult to change that now," but continuing with all that money and human capital (stress, choosing, scheduling, installing tile, etc etc) eventually leads to regret in "should've done it another way when I had the chance." But maybe you have the perfect layout, so then . . . Because you have the shower and toilet wing walls creating "darkness," I would consider the vanity lighting as part of the main lighting, on the same switch. So the vanity, shower can, and can in front of the shower all switched together. The location of vanity depends. Standard toekick, furniture style, or floating? You will have 2.5' of extra space to either fill or make symmetrical. What kind of lighting and feel of the space do you want? Sconces? Over-vanity style (hollywood lights lol)? General throw of 6" or 4" cans or tighter cones of 3" trims? Ductwork/piping in joist spaces and ceiling height? Dark matte/bright white glossy tile everywhere? That all makes a difference on how many/where.

I'm not the OP, but I think the thing in front of the window on the right is the radiator, probably costly to move. You're right that some of the clearances are difficult. Here's an idea that remedies the issues you point out. I've changed the swing of both existing doors to open out, partly for clarity about other details in the drawing. The shower door could open to the side to avoid conflict with the radiator. It's not ideal to have it open into the path into the bathroom, but I've lived for years with a shower door that does this, and it's OK. A better choice might be a corner entry shower or curved shower. Something like this: DreamLine Prism 72-in H x 34.125-in to 34.125-in W Frameless Pivot Brushed Nickel Shower Door (Clear Glass) in the Shower Doors department at Lowes.com They'd have to be careful about whether the shower size and shower entry width meet code requirements. The door at the bottom of the picture can be standard width, shouldn't be reduced to 24". Good bathroom design recommends at least 32" clear width. I think code where I am requires 28". If you have 24" you can keep it unless you remodel. (I have a 24" door on a powder room.. It's *narrow*. I wouldn't recommend it to anyone.) I've moved the sink as you suggested, and rotated it 90 deg. I think this gives better space in front of the sink, and it allows a wider vanity. However, this seems like a lot of wasted floor space in such a large room. Here are a couple other ideas playing with dividing it for bathroom and storage. The choices depend partly on what OP wants to store, and their priorities. These are starting ideas to be tweaked. In each of these, there's the option to do away with one of the doors, either the one from the room at the bottom into the "hall" or the one from the "hall" into the bathroom. Plan 4: Assumes there's flexibility to move the door at the bottom. Small corner sink to allow the required clearance in front of the toilet. Sliding doors on the shower avoid the problem radiator. Plan 5: Assumes flexibility about the door on the left wall. It has a small vanity (I've drawn it as 18x16) in the nook near the radiator. I could debate which way to swing the shower door. This idea gives both deep and shallow storage areas. Depending on preferences, this could be changed to accommodate a 48x32 shower with bypass doors, by reducing the size of the storage at the lower left. I agree with Patricia that it would be helpful to know what the rooms are that connect to this, and how it fits into the rest of the house. If the intention is that it's mainly a bathroom for coming in from working or playing in the yard vs. a main guest bathroom, etc.

You may have already thought about this, but dimmer switches will make whatever lighting scheme you decide on more flexible. Also, think about where furniture will be before placing the recessed lighting. 18 months ago we moved into a 25 year old house that had a finished basement (also with some windows, like yours). While they at least had dimmers on the recessed lighting, the placement of some of the cans was puzzling, even considering where they had their furniture when we saw the house before purchasing (the previous owners did the basement fit-out). I like the one room that has cans in the four corners and a central fixture which is a semi-flush 3-light (the cans are placed about two feet from the walls). The result is that the room is lit very evenly without the use of any table or floor lamps. I use the room for an office so I have a desk lamp for task lighting. Even if you don't use the other part of your basement, if you finish it so it could be used for a family room it will be good for your resale value. The next owners may want to put their teenagers down there with a big television. :-) I love the idea of the full bathroom. That is something I don't have in mine.