I’ve long recommend to visitors that driving in DC is a bad idea for the uninitiated and to instead take Metro.
Metro is relatively simple to figure out, comparatively inexpensive, hits a good chunk of the places visitors want to take in. What's more, it’s concrete, both figuratively and literally. Their is no doubt when you are in a station, the station is clearly named, and the whole thing is color coded. Sure, there’s a bit of confusion for visitors about which side of the platform to get on the train from, and the pricing is becoming increasingly complex; but the average tourist can get on, spend a minute or two looking at the map, and get where they’re going.
The problem: the Rail system doesn’t go everywhere. Georgetown, the Frederick Douglas House, the National Arboretum, Adams-Morgan, the National Cathedral, and, yes, the Lincoln Memorial, are but a few of the incredible things Washington has to offer that ill-served by the train. They all, of course, are accessible by Metro Bus, but most visitors shy away from it.