I am going to post this here in case anyone else neds the info.
We are travelling to the meetup via RV and the RV park that was listed in this thread is a year round park so they don't have opening. So I did a lot of searching around before booking a place. There are a couple of options.
KOA- about 20 miles
Washington DC / Capitol KOA
768 Cecil Avenue North - PO Box 9
Millersville, MD 21108
ok, but you will have to travel the beltway to get back and forth (this was our 2cnd choice)
This is where we booked Travel Trailer Village
It is about 20 miles SOUTHWEST of Alexandria and is GORGEOUS! Is thrilled to have all of our yorkies there and run by the nicest people! AND it is CHEAP and has free wireless and there is a 10% discount for age 62 or AAA. phone # 888-737-5730 Ask for Miss Avis and tell her you would like a spot near the other people there with yorkies (that will be ME (Sonya Shaw) as well as mypreciouspups (Anne) and Annabella's Mom (Nancy). If you give them my name they will reserve a spot by us. Some of us are also towing vehicles so there should be plenty of room to carpool into the meetup hotel.