Hey MJ....you and I dress similarily, although I tend more towards the Orthodox Jewish style...here are some great resources for long skirts and simple tops:
One is Orthodox Jewish, one is Islamic, and the last two are Mormon!! I have clothes from every single one of these, and love them. Theses constitute my "uniform". They offer many Plain colours, but their length and modesty are of the sort that you cannot find in mainstream stores.
You may already know about there, but thought I would share when I read your post describing your present day dress.