The Washington Hilton is in Kalorama, about 4 blocks north from Dupont Circle. Off-peak, it should be no more than 20 minutes and about $12, but both those numbers could more than double during rush hour.

Picking up the Metro from Rosslyn would be far better, as the ride would be only $1.85 – $2.40 and 20 – 30 minutes depending on time of day. The Q St NW exit from the Dupont Circle station is about 3 blocks from the hotel.

Alternatively, one could take the Washington Flyer ($10, 25 min) to West Falls Church, then the Orange Line to Metro Center and then the Red Line to Dupont Circle ($2.40 – $4.25, 35 – 50 min). The chief advantage here is that the WashFly bus is far more pleasant, more frequent, and more reliable than the Metrobus.

The Rosslyn-Dupont Circulator stops a block south of the Circle. While this is the absolute lowest price option ($6 for the 5A, $1 for the Circulator), it's may not be the most cost-effective here when you factor in time: up to an hour waiting for the 5A, then the snail's tour of Georgetown (non-rush hour time quoted for this route is 1 hour 9 minutes eastbound!), then navigating 6-7 blocks uphill on icy sidewalks with luggage.