Replying to Siver pants?

Ok, i tried on a pair of siver ski pants at the store today and they were mediums. they were definetely tighter than i want them around the waist. I could button em but they were definetely tight. The length was alright though. Now what i want to know is. Do their different styles run pretty much the same as far as sizes go? And mainly, will a large be loose enough, i want to sag em but i also dont want em to drop straight to the ground without a belt. So i dont know if i want L or XL. Like, is there a big jump in waist sizes between the different sizes??? Any help would be great thanks