We have been to the Filene Center at Wolf Trap many, many times. Acoustically, it is one of the finest venues in the area. On this night we enjoyed Celtic Woman and the show was wonderful. My beef has always been with the parking situation. It is not the best, but I don't think there is any room for improvement, except with regard to availability of handicapped parking and shuttle carts. If possible, they need to add another handicapped parking lot adjacent to or near the front orchestra area.
If you want to park close to the Center be sure to arrive at least 90 minutes prior to show time if at all possible. Cart shuttles were sporadic at best. We ended up walking down the stairs to the orchestra area from an upper lot because the carts were full, which wasn't easy for me.
After the show it was much worse. Myself, along 20 or more other people, many elderly, waited (standing) over 45 minutes for a cart to take us up the hill. The cart never came while we waited and when we heard it would be at least another 15 minutes we gave up and slowly made the trek up the steps to get to the parking lot. As well as the uniformed officers and Wolf Trap staff guide the cars through the maze of roads and parking lots, bring a LOT of patience after the show because the traffic is a nightmare.