You can pay with coin to park anywhere downtown, and after 7pm or 9pm depending on where you are it's free. Parking in a lot at any of the Metro stations that have more than 4hr Kiss and Ride parking requires a SmartTrip card in their garage, but the Kiss and Ride is meter based and should suit your needs.

And of course you can buy a fare ticket with cash.

www.wmata.com

Cash is KING. Be sure to dispose of your receipts, but pay everything in cash. Also, taking the metro is an excellent idea as the traffic in DuPont Circle can prove to be a bit problematic.

Enjoy your session!

I live near Dupont Circle and almost always drive there and find parking when I go there during the day, and in the evening it's worth a chance depending on what's going on.  There are 1, 2 and 4 hour meters depending on the location but within walking distance of hotels restaurants and watering places.  Check the side streets off Conn Ave on both sides of Conn Ave just north of Dupont and you might get lucky.  Even if you have to walk 3-4 blocks it's worth it, and if you get stuck you can usually find a garage, although the tariff is high.  Washington downtown parking and traffic are a pain but nothing compared to NYC, for example. Good luck.

Much of that depends what time of day (and day of the week) you are looking at going there.

Daytime I have never had much success parking there though some others have.  Evenings isn't near as bad if you look along O and P streets heading east of DuPont (might have to go 2-3 blocks) or on 20-23 Streets south (again, about 3 blocks).  In summer it's a comfortable walk.

one of 6 Metro parking garages where you can pay by credit card when you leave.  Most require the SmarTrip card, for which you must pay $ 10, with $ 5 for the card & $ 5 value on the card; but at Shady Grove you can pay with credit card when exiting (believe it is $ 4.50/day but may have gone up).  I'm including the URL for the Metro parking info page.  If you drive into Dupont Circle area trsffic csn be s problem, & driving around trying to find a metered space with an appointment time approaching can lead to a desperate dive into an expensive garage.  I'd park at Shady Grove & take Metro; virtually all of the good hotels in Dupont Circle are an easy walk from the Metro (I've seen providers in 8 different Dupont Circle area hotels).  Leave plenty of time; Dupont Circle has several bookstores & coffee shops in which to kill a few minutes if you're early.  Good luck & have fun!

They were out today and they shut down that station. It has what I think are the second longest escalators in the western hemisphere (Wheaton is the longest) and when they break it is quite the work out climbing all the way to the top.  Not my idea of a fun cardio work out.  If I want to breather hard raise my heart rate and work up a sweat I know a cute little redhead that is just the ticket

I think driving would be best. There is usually  parking on residential side streets around Dupont Circle.  However, some are metered and others are near a sign saying a residential permit is required during the day. Of course it helps if you drive a compact vehicle. Also, don't forget to bring quarters for the meter.