Stayed here for a two week business trip. Had originally opted for Comfort Suites on the other side of 66 since it was cheaper but it was booked (that location is better for restaurants and bars that are within walking distance so you don't need a designated driver.)
Courtyard Marriott Battlefield is close to Battlefield Park and close to the highway but you don't get any highway noise. Uno's is close by and there is a $3 discount if you show your room key and you also get Marriott points for each receipt that you bring to the front desk.
The hotel is clean and rooms are well-kept. The front desk attendant named Edna was very friendly and so were the breakfast servers. Breakfast was included in my room price ($8.95 separately I think.) The breakfast selection consists of various breads, oatmeal and assorted toppings, scrambled eggs (w or w/o cheese), sausage links, bacon, hash browns, salsa, make your own waffles, assorted cut fruits, yogurt, whole, skim, 2%, choco milk, coffee, cranberry, apple, orange juices, and small canned grapefruit juice. During my stay breakfast was usually open for service around 6:15am on weekdays. There is one washer and one dryer ($1.50 per load) and the washer comes with complimentary detergent (the washer water routes through a container with a solid block of soap which then empties into the washer tub) but you can purchase detergent packs at the front desk. The pool/spa area has a lifeguard on duty so the area has rather short hours of operation and no glass or alcoholic beverages are allowed. There is a small workout area with two treadmills, free weights, and a spinner as I recall. Overall a comfortable place to stay. I had a 9AM flight out of Dulles on a Friday and DC inbound traffic is horrendous every day getting onto 66 but by leaving at 6am I got to the airport, rental returned, flight checked in, and through security by 7:20 which left ample time for a leisurely breakfast in the terminal before flying out.

I stayed at this Courtyard for about two weeks. The outside of the hotel had a California look to it (which I loved). As I checked in I was greeting by a very nice group of staff (extremely nice). The rooms were very spacious and the beds were terrific. I will certainly come back!

Stayed here for a two-weeks work trip. Room was spacious and clean and the continental breakfast served was great although more variety could be added as it got a little boring being served the same food over and over after two-weeks.

Nice and quiet place to stay, away from the hustle and bustle of town within an hour's drive from D.C. Could be a little cheaper considering its location from the heart of D.C. but overall value for money.

Note to international visitors: Driving is a must here as taxis are hard to come by outside of the city center.

This hotel is good for what it is--very close to the Manassas/Bull Run battlefields, provides comfortable beds in well-maintained rooms, and available for a very reasonable price.

Breakfast is above average and was included in our room price.

There's an indoor swimming pool and jacuzzi, but they keep somewhat narrow hours (not open until 10:00 am) and they feel like they're in a cave despite the windows.

This isn't a spectacular property, but it's definitely comfortable and a worthy option if you're in the area.

We had a little trouble finding it, since the signs for it from the road are very poorly marked--it's in the same turnoff as the other hotels in that immediate area.

Room tip: ask for an interior, courtyard room. Forget about spending extra for a balcony if you're facing the exterior (parking lot with highway near by).