There are nice parts of PWC, but there are a lot of not-so-nice parts. Everyone I know there complains a lot about local governance and quality of the schools. A large number of my neighboors moved here because of how bad it was getting where they lived in PWC. The troubled areas are mostly Dale City and surrounding area. The Lorton/Occaquan/Lake Ridge areas have become quite mid-upper class lately.
I looked at a few homes in PWC before I bought mine here, could have had a bigger house a half hour closer to work for the same money, but I would have been the only white guy in the hood and wouldn't have been too comfortable with my wife home alone. Here locks are optional and my wife is happy going walking any time. Its really a matter of preference, but I really don't care for areas that are even semi-high crime.
Perhaps saying to avoid PWC all together would be a bit much, how about be very carefull about the specific area in PWC you might end up and if you have kids that will be in the public education system look into that as well.
I really really like the Fairfax Station and Clifton areas - they are pricy but super nice and clean. Locks totally not needed (seriously, our back door didn't even have a lock when we lived in Fairfax Station). Also most of the lots west of Ox road are really big - 5 acers is the norm (protected water shed or something). Most of them are over a mill now, but some are still not so bad. You might look at places around Sandy Run park (van thompson road - zip 22039) for semi-affordable big-lot homes. The other side of Ox road (rt 123) is also quite nice, just smaller lots. Also usually close to a mill, but vary a lot depending on age etc. "Cross Point" is a nice, but price subdivision.
this place
http://www.realtor.com/Prop/1067262668
is in an older subdivision that borders cross point. Its about 15 minutes from GMU and downtown fairfax, 5 minutes from a new golf course, lots of parks near by (at least 3 in a 10 minute drive).
Oh, also be aware that there are a lot of huge, fancy cheep houses around Ripon Landing - reason being they are built around a sewer treatment facility and surrounded by sorta bad areas. Stinks in the summer

uke
I don't know much about the areas west of alexandria (herndon, loudon etc). Burn could fill you in if your interested, but that's probably not quite right for you unless your working on the far west corner of Alexandria as the commute would suck.