I'm trying to get some pants (jeans and comfy joggers/athletic pants) for my son and I'm discovering everything that's long enough for him falls down. I've ordered a couple pair of slim jeans from Old Navy to try. He does NOT want skinny jeans style, just comfortable things that stay up. He's a size 6 or 7 in most things and is 48.5 inches tall with about a 21.5 inch waist. Any suggestions for styles or stores to check out?