Renovating interior doors

Paint or Stain????

I've seen where wood molding was cut and pieced to make a wainscoting type pattern on doors &/or along a long hallway. You should be able to find directions on YouTube or elsewhere online.

Have you thought of painting them black?

Do a search for using strips of molding to create the look of wainscoting on the doors to give them a decorative look.

If they are in a mud room or kids room paint them with chalk board paint and give the kids chalk or put your to do and shopping list on it.

Depending on the style of your home, you can glue and tack trim pieces to create the look of panels, or you can sand them down, prime them and paint them white or if you like a more contemporary look paint them black and the trim white.