But it could always be improved! Every time I look at the system map I mentally play connect-the-dots and create new and useful subway routes. Greater Greater Washington likes this game too and resurrects a map of proposed Metro additions from the early '90s. Click the image for the full-size version; the current system map is here.
This fantasy version has some nifty features (the Dulles connection and the outbound routes to Baltimore and Annapolis would be great, and the ring line would do miracles for Beltway traffic, I'm sure) but I have to take exception to the Georgetown-Chevy Chase-Wheaton route.
Granted, a Georgetown station would be super-popular and would help the kids who want to go drinking on the weekend not have to pile into taxis to get home. But there are so, so many places in DC more in need of a Metro stop than these. Not for nothing does ggwash dub this the "rich white people's line."
Instead, we really should head north from Georgetown up to Cathedral (drop off some tourists) and then turn east back to Woodley, cross the Rock Creek into Adams-Morgan (another hit with the bar and restaurant crowd) and connect to the Green Line at Columbia Heights. From there the line could turn north up 14th or 16th streets towards Takoma and north DC.
Or, alternately, the route could continue into Northeast towards the Washington Hospital Center (currently not served by Metro!), the Rhode Island Ave station, turn south through Trinidad and Capitol Hill and connect to the Orange/Blue Lines at Potomac Ave. It could even (gasp) jump the river and add some options for the folks in Anacostia.
Anyway, those are my fantasy picks. Granted, a tradeoff does exist between expanding service for suburban commuters (which would take a lot of cars of the road) and creating a truly usable public transportation service for city and inner-suburb people that need it most (i.e. those hardest hit by rising gas prices).
Realistically, the politics of expanding Metro revolve around getting either Maryland or Virginia to pony up some cash (hence the planned Silver Line to Dulles or the Purple Line proposal) whereas increasing transit density and usefulness for DC residents falls mainly on our already overstretched tax base. Still, these types of investments are bound to payoff in the long run.
(via transit pornographer Matt Yglesias. More Metro extension proposals found here.)