I don't recommend doing either of these activities if you have bad knees. As an aside, I encourage you to avoid using an elevator whenever possible. A set of 10 or 15 of these two or three times during the day will greatly improve your ability to stay on your toes during a match. Finally, we come to distance running. There is a place for this activity in tennis.
Distance running does help develop endurance.
However, the distance one runs should be limited. If possible, these miles should be run on something other that concrete or other hard surfaces. I like to run on a cinder track, a rubberized track or on dirt trails. The more cushioned impact on these softer surfaces allows my knees to handle this type of running with less discomfort. In putting this all together, let me give you a sample regimen that is based on a six-day exercise week.