My dog (70 lb. one-year old intact male GSD) loves to chew, and his favorite thing to gnaw on are his Nylabones. His favorite is the Nylabone keyring (the BIG one). He's had it since I got him at 7 weeks, and he chews on it at bedtime almost every night (I keep it in my room on his bed). It has teeth marks all over it, but it's still intact. He also has a Nylabone "wishbone" (also the big one). It's another favorite. He's not big on the kong - once he's gotten the peanut butter or whatever stuffing I use out, he could care less about the toy itself.
I also just bought a Katie's Bumper toy (I think it's made out of heavy duty nylon?) I bought a big octagon-shaped one - it has a cutout in the center, and can be used as a flyer, but he just chews on it. I've only had it a week, but he has chewed quite a bit on it, and you can't tell by looking at it, although he already broke both of the squeakers in it. However, I wouldn't leave him with that one unattended, although it seems pretty indestructible.
P.S. I NEVER give Kodee any type of "leathery" chews - no rawhides, pig ears, etc. Too much chance of intestinal blockage.