Adjustable waists are great, I have boys with no backsides or hips, can only buy pants with adjustable waists.
DS1 was a bonds baby, they had just started their real funky range, he lived in and always got comments on how cute he looked. The legging type pants are great.
I just got them both some Cargo type pants from target that have the elastic at the bottom cuff, they came in all the boys range from little to big.