You could do squats in place of the jumping jacks if you're getting bored with marching in place. If you want to increase intensity of marching in place without any high impact (bounce), then do knee lifts. raise your knee is as high as your waist. If that's too high, then lift the knee as high as you feel comfortable. you don't have to go fast. take your time.
There are also modified jacks. You can see a demo here. Just use the arm movement and step side to side. www.youtube.com/watch?v=lNssa8g3GEc