Now that Viggo is Aragorn, I'm not sure who else would have done the character better, visage-wise. Viggo is not young looking, but nor is he old. He can dress up, when around his She-Elf, and he looks like a man that an elf would die for. When he's with his traveling buddies, he appears rough enough to handle his own. Viggo gave his battle scenes realism - he didn't appear fake.
My only complaint is his voice, as at times it doesn't appear kingly. Best (and most readily-available) example of his voice being off is when he says, "orc," at the end of FotR. It comes out too nasally, and to me kills the scene a bit.
And in regards to Viggo/Strider looking like he's walked the walk, I would note that
Bear Grylls, my new hero of 'Man vs Wild' fame, has lived the life of Aragorn and yet looks...don't know the best word...but handsome enough. If you see a picture of Mr. Grylls, you will note that he too has designer face scruff.
One of book covers (can't remember which), and the Bashki movie have Aragorn looking too 'Roman' to me.
Regardless, Peter Jackson's version has overwritten my original images on my organic hard drive, which is sad.