Is the shelf indicated underneath the stairs a place you're considering an amplifier/data cabinet? If you want truly minimalistic you need to have an equipment rack somewhere out of sight but wired to your TV or projector.
It's probably worth running a conduit out to the ceiling where a projector might go, even if you have no intention of using one yourself.
One regret I have from finishing our basement last year was not putting pot lights into the bedrooms/office. I just went for the traditional one-overhead fixture and it's kind of dark. If you have any intention of using the space regularly, it's almost impossible to have too much lighting.
I say almost because I definitely put too might light into a small corridor with a lower ceiling due to a bulkhead and it's obnoxiously bright.
Otherwise, my favorite feature of our basement was the ample storage/workshop space we put in. With a detached garage, our basement has become the most secure place to store valuable items like bikes and tools.
A lot of newly developed homes really are stingy on the storage/workshop space downstairs, which shows well when you walk through, but at least for our living needs, wouldn't be sufficient.