Lewinsville Montessori on Great Falls Street in McLean (and not far from Tysons) takes new-borns as young as 3 months. It is a 12-month program, which is very important when both parents work. It opens reasonably early and is open until maybe 6pm.
They take off for a winter break between Xmas and New Years and they also take most (all ?) Federal holidays. They have well-equipped fenced playgrounds outdoors. Parents provide milk/formula and supplies (and when older, provide lunch instead of formula/milk).
For the youngest, it is really mostly day care. As the kids grow older, the classrooms have more and more materials, especially Montessori materials.
One important logistical note: They rent from Fairfax County. A different facility (Westgate Children's Center) is in the same building (also renting from the county), and shares the entry lobby. From that lobby, one door goes to Westgate, another door to the Fairfax County Senior Center, and a third door goes to Lewinsville Montessori. So when you visit, be sure to read the signs on the doors.
We were very happy. Having safe/reliable 12-month child care was critical for us, since we both work full-time.