Usually basement finishing is not an added actual value but IMO a nice thing to do . As for the bathroom as mnetioned if a bedroom is planned then add the shower if no bedroom a 1/2 bath is all you need . Can you post some pics of the basement like it would be nice to know is this a walkout or not, Where are the windows , what size are they? A bedroom needs a window large enought to use for egress so that could be the issue that makes this decision easier.Also i agree if you have kids then sleepovers could use a shower so I guess more info please.

This is not a walkout basement. Yes, anything below grade isn't part of square but curious how value is added to a property and how having a bathroom there is valued. I don't have a bedroom in the basement, just a very large open living space with regular basement windows. We might get a sleeper sofa for guests or maybe in the future if we add an addition above grade we'd excavate for an extra room in the basement to make an office or bedroom.

I think you do what works for you not some imaginary buyer down the road. We had a 1905 house and to put a shower in the basement was so cost prohibitive that we did not do that even though we had a guest room there . The guests used the shower on the main floor noyt ideal but never really caused issues .Our guest room had a nice large window for egress and the resyt of the basement had no windows but with really good lighting it was amzing how people never realized there were no windows but that made for a perfect media room

These are pics of the basement

I don't think it matters what all else is in the basement. What matters is when you have the family all together for say a holiday--how many are you, how many showers would come in handy? I would say 3thousand for a another shower will be money well spent when you need it!! I know ours is.

@Patricia Colwell Consulting how tall are those ceilings? I'd love to put egress windows in my basement. Amazing job!