Trekking Poles or No Trekking Poles

When I began looking into the things I would need for this hike, I was on the fence about trekking poles.  I knew they were a popular accessory, but I wondered how useful they really were.  Honestly, they seemed more like a cool toy than a trail necessity.  Then I began to read about how they can help take some of the stress off your joints- like your knees and hips.  And since I have pretty beat up knees from various horse riding injuries, I figured trekking poles might be worth the try. My brother, who is one of the 7 going on the trip, got me a pair of poles for Christmas.  I began using them right away.  No, really, I used them in the house.
I took them with me on my first hike of the New Year.  I had been pretty sick the night before (and I was still running a low grade fever when I went out on the hike) and I was feeling a bit run down.  The poles were a Godsend on that particular day even though we were hiking a very easy trail.  I also discovered that they are extremely useful in distracting 8 year old boys from whining about how much further and if we're almost done.  And they helped him maintain his balance and gave him confidence in crossing a small stream.  Score one for the poles. 
Since then, I've had them with me on several occasions and they've been used by a few people.  On a winter camping trip with my son's Cub Scout Pack, one parent who had recent arm surgery used one of the poles to help her with balance and keeping her footing (I used the other one for the same reason- ice was everywhere).  I've taken them on each of my hiking trips, and it's true that they help build up your upper body muscles.  Each hike not only are my legs feeling sore, but my arms and shoulder are sore from using the poles- which is a good thing.  The last hike that we went on was closer to the terrain we'll encounter on the AT, meaning it had a few steep inclines.  The poles were a definite benefit in hauling my butt up the hills and took strain off my knees on the downhill.  The trail also had quite a bit of ice covering it so they were again useful in keeping my footing.  I'll definitely be taking them with me on the big trip, and I'm also going to be getting a set for my husband and my 8 year old.  Then maybe I can use both of my poles at the same time instead of sharing.
So, basically I'm saying Yes, trekking poles are definitely worth having on any trail.  They build upper body strength, take strain off joints, help with balance (a plus I'm guessing when carrying a pack), help cross streams and counteract boredom.  And that's just in the winter.  I'm sure they're helpful in the event there might be a snake around, an unleashed dog, a bear, mud, etc.