Hi Carol,
I was in D.C. last September. Before I left I asked if anyone in that area would like to have a meeting while I was in town. Several people responded and we had a nice time. It doesn't appear that they have continued to meet, but you may find there is a desire to have a monthly group
All I can tell you is how the Sacramento meetings came to be. Four years ago I noticed that a group of people from this Helpline (now called a forum) were meeting monthly in Denver. I thought it sounded like a great idea, so I posted asking if anyone in the Sacramento area was interested. There was a good response, so based on the location of the responders we set it up. We just went with the 3rd Saturday of the month, and chose Panera Bread because they don't have servers and they do have wifi. After two months and more people joining us we changed to a more central location for the expanded group. We have been meeting there ever since.
The thing I think is really important is consistency. It is always the same day (3rd Saturday), same time (10:00) and same location. Some of our regulars don't get on the forum very often, but they always know where and when the meeting is.
If you don't get much response, give it time. Our first meeting was about 6 or 7 people. We have grown. We fluctuate from month to month, as people are sometimes traveling or have other obligations. We've had up to about 17 people. Personally I like it a bit smaller, as it's hard to talk to everyone with such a large group. We are very informal. We don't have an agenda (well, some might have a hidden one...;-)). That's what works for us.
If you don't get a response after trying to put something together here, try to see if there is a local Meet Up travel group.
Good luck!