If you were thinking of crossing the Potomac at the Wilson Bridge, during evening rush hour, instead of sticking with 395 North, DONT. Traffic over the Wilson will make you wish for the good old days on 395.
But if you insisted on doing so, once across, you would simply head north on 295, all the way to East Capitol St, and you're there. THere is no easier approach to RFK during the evening rush hour than from the Beltway and 295.
Great for the folks in Southern PG (Oxon HIll and points south) but not accessible from Va due to bridge traffic.
If from Richmond, you wanted to come up 301 across the Morgantown bridge, then jump over to 210 from Waldorf, this is a viable alternative for you.
Stay away from 301 / Branch avenue if possible.