Besides a nice smell, I think real trees are a hassle and suck up land that could be more productively used. As the parent of a young one, too, you have to think about whether he not only will climb the tree but also will touch it, get sap on his hand and in his mouth, drag needles through the house (and needles get sharper and more painful once they're dried out and buried in carpet for feet to find months later!). There are beautiful and realistic artificial trees out there.
One thing to remember -- anchor your tree if you have a climber! Our daughter wasn't even a climber but for her safety, when she was small, I tied a thin rope around the tree trunk in the center and ran it out the "back" of the tree (side nearest the wall) and tied the other end to the leg of a very low, sturdy and heavy table. If she had messed with the tree, it at least would not have fallen all the way over on top of her, and the table was one I knew could not turn over because it was so low. I made sure the rope was as taut as possible. I am suprised that no one makes some kind of product designed to anchor Christmas trees for household with small children or active pets! It makes sense to me.
Another option: Think through whether you really will spend much of the holidays saying "No, no, no" and watching your son like a hawk and fearing that if you're out of the room he might slip in and climb or pull on the tree. That would not make a happy or relaxing holiday, would it? There is no law saying you have to have a tree at all. I adore trees and ornaments but if my child had been a climber/toucher/tugger, I would have done without one for a year or two and displayed fragile, beloved ornaments by stringing them on heavy, wired ribbon and then stringing that like a garland high up on the wall. Like I said -- I love trees but is it worth having a tree if you're constantly worried about your child's safety? No tradition is worth that, and besides, you'd get to have a tree back in a year or two when he is perhaps past the climbing/touching stage. I'd rather get creative and display ornaments another way, than have a tree because I've always had one -- but not enjoy the tree because I was worried about a child getting hurt.