So the three colors of cabinets is throwing me off but I think you will need to change the spindles for sure on the staircase and that is not a cheap job.I would do very simple black metal for those , do the treads the same as your mian flooring and remove and replace all the trim with something much more modern .

You really like to mix your materials! That would call for the on trend wrought iron spindles, plexiglass instead of spindles, iron rope instead of spindles with metal balusters'.... perhaps but sorry nothing about changing out a staircase is inexpensive! What are your countertops? I just saw a designer use the same quartz composite of her new countertops as stair treads......

Strip wood to light wood (kitchen cab) paint spindles black (kitchen cabs).

Thank you for all your advice!