We're a military family; we live in CO Springs now but we lived in the D.C. area (Arlington, and then Loudoun County) for four years.
I can tell you that at the time we lived in Loudoun and were interested in buying, we had a budget of 300,000. We worked with a realtor for two year and could not find not. ONE. single family house in the entire county for that price range. And because of traffic, Loudoun was definitely would be over an hour's commute time into D.C. because it would take about an hour just to get to Arlington.
If you wanted to greatly stretch your commute time, you can certainly look much further out and have better luck to find something more cost-effective but you will be looking at commute times of two hours easily due to traffic.
I personally enjoyed living in Loudoun County. We lived in the South Riding subdivision with was extremely family friendly....about 30% of SAHMs, lots of young families and a lot of family friendly activities in the immediate area (four community pools in South Riding, a great brand new community center 10 minutes away, a brand new library 5 minutes away, a weekly live music time in a coffee shop about 15 minutes away, a family farm with kid's activities etc. etc.). Schools in that area are some of the best in the country. However, the rent on our three bedroom townhome was 1800 a month, and our rent for our four bedroom detached home was 2100 a month.
And as an FYI, living in that part of VA is expensive, period. Cost of living for activities, groceries, utilities and pretty much everything is elevated. We lost over 16,000 dollars in income when we left VA for Colorado Springs, but we actually gained about 200 dollars a month in spendable income due to the drop in cost of living expenditures.
When we first moved to the area, we actually lived in Arlington, VA across the street from the court house metro station. Believe it or not, while I otherwise totally prefer space and grass, I greatly enjoyed living in Arlington because I never had to use my car and traffic in the D.C. greater area is so bad. I literally used my vehicle three times the entire year and a half we lived there. I was within a 10 minute walk to three grocery stores, a barnes and noble, over forty different shops, two community parks. The movie theater was literally across the street, as was the CVS. We walked to church. Anything else we wanted to do was a few metro stops away--- we took the metro to the mall, metro the doctor's office, metro into D.C. to the spend days at the Smithsonians, metro to watch the Capitals play--- and we never had to worry about traffic or where we would be able to park our car.
Ironically, my husband's job was in Loudoun County, and even doing the reverse commute it took him 45 minutes at peak travel times to get out there and back. We hated the additional family time we lost to the commute and that is why we moved. If he had worked in D.C. or Arlington, we would have done everything we could to keep living in Arlington. So, you need to decide what is most important to you--- family time together or more space (and no judgment, it's a personal decision). But it is definitely more expensive in Arlington--- we spent 2200 dollars on our 2 bedroom apartment (with pool and community room). To rent a house would have easily been in the three thousand dollar range. We could literally see the metro station about 50 steps away from the front door of our apartment complex however, which added greatly to price. But the convenience could not be beat.