I second what DaveK said. My brother used to live in Kensington (near Newport Mill MS) so I rode a bit between his place, my place in downtown SS and where I worked in Bethesda. From his house I made my way west on neighborhood roads over to Beach Dr, down that to Connecticut – ride the sidewalk for a mile or so for a shortcut – or go all the way to the Georgetown Branch trail.
If you want to avoid riding gravel daily to cut down on dirt and grime, I also did a road route through the neighborhoods that started by going up Rollingwood, south of East-West Hwy and ending at Wisconsin and Leland St. From there you can get on the CCT and go to Georgetown.