I haven't tried Paris Baguette but I suspect they have good pastries. Haven't been in years but the above mentioned Pastries by Randolph was great (and may still be) and the same goes for Heidelberg Bakery in Arlington. A good bakery that I have been to recently is The Swiss Bakery and Pastry Shop in Springfield.
If you are looking for cakes, Victoria's Cakery in Fairfax is very good (parking is sometimes an issue).
You could also pick up pastries from the local Wegmans, Whole Foods, or Trader Joe's.
