Admittedly, this wasn't a client question, but one from a writer doing an article for a womens magazine...but it is a question that at least one person has, so here are my short answers:
1. Aside from the traditional options (I am thinking basic forward and side planks), what is your favorite unique way to plank?
2. How does this increase the burn and does it help strengthen and tone other muscles aside from the core?
3. Any other tips to get more out of your planks?
One of my favorite ways to plank is to add in knee taps. Moving the limbs during the exercise adds additional elements of stamina, balance, and increased muscle targeting, and break up the monotony of simply holding the pose. Adding in knee taps also involves the obliques, psoas, and quadriceps for increased muscle activity, and can be modified for beginners or more advanced movers by changing where you tap the knee; if you're just starting out, add an alternating knee tap to the mat. For a more advanced movement, tap an alternating knee to your elbow.
Other important planking tips:
Form is key with plank, so use a mirror if you have to until you know it by feel. Maintaining a strong line from the crown of the head to the tailbone is important, as is stability in the shoulders and hips, and equal weight distribution between the upper and lower limbs.
Take a break when you feel it failing. Exercises can get dangerous when you stress the muscles beyond the point of performing them well. Building onto your time or number of reps is a better way to go.
When in doubt, modify. If you feel your low back sagging or hurting, your shoulders are shimmying, or you can't take a full breath...modify the movement. Great alternatives are to keep both knees down, or to perform with upper limbs up on a bench (or your coffee table). Once you can get to a minute of planking with a modification, attempt the full version. You'll find that you're much more stable, as you've built up the muscles in a safer and more efficient way.
I personally really like planking, because it's a great time saver. I mean, it basically hits every muscle at once, and if you move it around as I suggest above, you incorporate many more aspects of your body's capabilities and increase the challenge (or "the burn", as the reporter suggests.)
And you can also do them anywhere. Bonus. And they're on the list of the things everyone should be able to do by the time they're 40. This is an imaginary list I just made up, but it's on there.
Everyone, hit the deck!