Hi, we have an 8yo female Staffie - she's a great example of the breed (utterly GORGEOUS! So loving and affectionate).
We've had her from a 9wo pup and made it clear from day 1 what was hers to chew and what was not. She's not as interested in chewing now she's in he senior years, but as a youngster had stuff like those knotted fabric chews. I can't think of the name; they're very tough, like a knotted rope with freyed ends. That's the only thing that would withstand the power of her jaws. Oh, and those Kang toys (really tough rubber). Hide chews were good, and hide strips, though I prefer them less as sometimes her gums would bleed when chewing enthusiastically :(
Now, chewing - yes, Staffies love to chew. It sounds as if your dog may need to re-learn (or even learn) whats okay to chew and what isn't. If he isn't chewing your kid's clothes but is chewing your DH's, that suggests to me dominance issues, and your dog is trying to assert dominance over your DH. Nip that it the bud. Whenever he chews something e's not supposed to, a firm 'No!' command should be given. Then give him somethinghe can chew.
When the dog chews something he's allowed to, give him tons of praise and maybe a doggie treat. Let him know when he's pleased you. Staffies really thrive on praise.
I'd also recommend playing with your dog that involves you showing dominance over him - particularly your DH. So play that involves touching and holding the dog whilst he's on his back, touching the top of his head, that sort of thing.
Also, if you're not doing it already, make him wait and sit for his food. It's all basic shows of 'place in the pack' for the dog. When they k ow where they are (i.e. at the bottom) behaviour should improve. Best of luck!