I like the extra 3' of usable space you added to the bar area. If you are able, the toilet and sink could be reversed. That way if the bath door is left open, your guests see a sink, not a toilet...this is considered a more upscale view. The other option is to keep the rest room door closed. A 24" or 30" bathroom door that swings against the bathtub would work great in your application.
It seems that the width between the stairs and the water shut off valve is a bit narrow to get furniture into your new living space. Do you plan on enclosing the valve with a floor to ceiling frame or are you going to use a bench seat to sit on top of the valve area. If you build a removale bench seat, TV stand or something that would lift off the valve, not only would you have easy access to the valve when needed, but you could get larger furniture and tables into the basemant living area more easily.
Good Luck on your project!