I live in Alexandria City and currently ride in Aldie, VA. Its a 50 minute drive from Alexandria to Aldie w/o traffic! I work out in the Dulles area and the commute is about 20-25 minutes from work and I only have the longer commute on weekends.
I don’t mean to burst your bubble but there is almost nothing close in to the DC/Alexandria area. Traffic is horrific! It can take 20-25 minutes to go 5 miles… If your schedule is more flexible I’d highly recommend leaving no later then 3PM to go to ride in the afternoon or it will take hours to get anywhere.
I have also boarded in Poolesville. MD and that was about a 35-45 minute drive from Alexandria, VA again w/o traffic.
Barns in Clifton, VA and Great Falls, VA are going to be the closest distance wise. Also there are a few barns in Prince Georges County (Upper Marlboro or Brandywine) those location will be about 30 mins from Alexandria, but again depending totally on the time of day you are trying to get there. If you get on the road at 5PM on a week day it will take you at least an hour to get there.
Feel free to PM me and I can give you the names of some barns in the Poolesville, MD area.
Also I’d suggest that if you are up this way to look at barns try to get there in a traffic time to see how long its really going to take you.
For transportation, Johnson, is fantastic! And who I used to ship my horse up to VA from FL. http://www.johnsonhorsetransportation.com/