We moved from Aldie, VA, two years ago. It's a bit west of Chantilly along Rte 50. Chantilly and Centreville are nice areas; if you can swing Clifton, it's a REALLY nice area (I have a friend in the Navy who lives in Clifton, so there are affordable places). We liked Aldie, but it might be a bit far for you. There's a BIG development called South Riding in Chantilly that has a lot to recommend it.
We used to go down to Manassas to hit a particular strip mall that was close to us (Aldie is basically just north of Manassas) and we also attended a music class at the JCC there -- but Manassas itself didn't seem like a great place. I know you said the school system doesn't matter as you homeschool, but it will matter for resale value of your home, and I didn't hear good things about the school system there . . .