VA Scuba in Manassas is pretty much the only shop that gets my recommendation for instruction in the DC metro area. It's a bit more of a drive than some other shops, but the quarry most shops in the area use for checkouts is in Haymarket anyway. Just take the belt way to 66, then west to the Prince William parkway, then take the first right onto Ball Ford Road and then right on Wellington Rd and look for the sign on the right hand side of the road.
Outside the strictly DC metro area, I also like Diver's Den in Baltimore. From Silver Spring it's just a simple drive up 95 to 695 to go around the west side of Baltimore to Parkville. They are about a mile south off exit 31A straight south down Harford Rd. They are easy to find with plenty of parking in the back. Diver's Den will probably do the checkouts at Dutch Springs.
Both shops are probably about equal distance for you.
There are a couple shops I'd avoid at all costs, but I'll save that for a PM if asked for an opinion on that.