We travel to Boston for an endocrinologist to treat my son's GHD. I wasn't overly impressed with local options and the person out of state was well qualified to treat possible genetic conditions (in addition to GHD), which was important to me.
I'd probably look to CHOP if I wanted a thorough opinion closer to DC. Once you start treatment, you only go twice a year (an easy trek out of state). I'm not sure why I've had such bad luck with local pediatric (and, honestly, adult) specialists in the DC area.