What always frustrated me about taking that route to the Suitland Federal center (and why I rarely did it) is that one has to climb in and out of the Oxon run valley at least three times (down from Wilson, up to Oxon Hill, down through Indian Head highway, up to St Barnabas.) (or alternatively, an even more convoluted way up through Congress Heights than back down to the Suitland Parkway, then up to Skyland, then back down to the DC border and up through the cemeteries)
My dream would be a spur from the bridge before the beltway crossing right down into the cove, then a trail that continues along Oxon run all the way to the Suitland Parkway. (and of course, a Suitland Parkway trail that continues to Andrews, but that is more or less in the planning books already)