I live in Germantown, MD which is about a 40 minute drive from downtown DC. There are some really nice muni trails out here. If you have a car and want to head out here on the afternoon of the 6th I can ride with you. The evening rush hour is bad in this direction so after 5 pm on the other days would not work very well.
I’m close to DC as well. If you want Muni, there are a few trails out in Northern VA - Fountainhead, Wakefield park, and Difficult Run/Great Falls. I wouldn’t be able to meet up on that Monday due to work, but I could get out of work a little bit early to meet up on one of the other days.
Germantown should be good. there is Schaeffer Farms, which has ~12mi of XC trails. it might not be quite as interesting as fountainhead in some ways, but at the same time, i think it would involve less walking up steep hills. there’s also Black Hills Regional Park, which is perhaps 10 miles (by roads) north of Germantown. Black Hills is a bit rockier and hillier than Schaeffer, and has fewer miles of trail (i think like 8-10 total). There is a connector trail between the two that would be 7 miles each way, but is currently closed due to construction.
Black Hills Park borders Germantown. There are trails right behind my house in Germantown that lead up into the park. The trails there are hillier and rockier than Schaeffer Farms but I think more interesting and fun.
The first Friday of every month, a “critical mass” bike ride leaves about 6:15 pm from DuPont Circle on an ad-hoc, bohemian parade through DC. I’ve been able to keep up with the group on my 29er, and would welcome other one-wheeled company. Next one is this Friday, 10/3.
Also, if Eddie or anyone else still wants to pedal around the sights on the afternoon of Monday, 10/6, chime in. In front of the White House would make for an easy place to meet. I’m flexible timing-wise, but proposed meeting at 2 pm.