A few quick comments (one already noted in e-mail):
-- route name VA GWMemPkwyFtH => VA GWMemPkwyMtV -- while there is an obscure Fort Hunt neighborhood along the route, Mt. Vernon is the far more famous destination at its southern end.
-- in DC GWMemPkwy, waypoint VA27 => WasBlvd -- VA 27 probably doesn't extend into the part of DC west of the Potomac River. Dave's draft VA 27 route file has the route ending short of the VA/DC line, while Mapmikey's Virginia Highways site has it ending right at the DC line but not reaching the parkway,
-- in Colorado, add ParkEntRd (and rename the US36 waypoint on TraRidRd accordingly), to account for the part of (pseudo?) US 36 within Rocky Mountain NP.
-- in DC and MD, maybe add Beach Drive within NPS-maintained Rock Creek Park 00 though that would make the usanp route set a bit Washington DC-centric, and definitely should get lower priority than the connecting Rock Creek Parkway.
-- in VA, maybe add the part of Spout Run Parkway north of Lorcom Lane in Arlington (south of there, it's VA 124), but it's pretty short and the above DC-centricity comment applies here too. At least change the SprRunPkwy point on the GW Parkway => SpoRunPkwy.
I was going to suggest, in Maryland, adding the Cabin John Parkway connector between I-495 and the Clara Barton Parkway. But it seems not to be NPS maintained, and moreover seems to be technically unsigned I-495X, so it might be better added to usai than to usanp.