I rode Columbia Pike regularly for 2 years until I moved. My opinion is that if you want to bicycle most days, you can get used to anything. I prefered riding home on Columbia Pike to riding into DC because I did not like flying downhill towards the 27 traffic.

If you were moving close enough to 4 Mile Run, I would probably take that trail. Obviously, you could also go down Glebe to 4 Mile Run. My preferred way was to turn onto Orme and then go over to the Pentagon that way. I used to cross at the light at Quinn in the morning and ride on the sidewalk for one block just to avoid the 27 craziness.