As an alternative, but maybe for when you get more comfortable with traffic, try Clarendon down to Lynn, then across the Key Bridge, then M st. and Penn all the way across town. I did it the other night on a CaBi (although I went all the way to Cap. Hill) and from Courthouse to Reagan Building took maybe 25 minutes. Traffic in the morning shouldn’t be too bad, but M in the afternoon can be a challenge. Again, it may not be the easiest route traffic-wise, but it’s fairly direct and sticking to the street helps avoid tourists, so it’s a good route to at least be familiar with.