Would love some YLF input on a rebuild your closet plan!

Have a heads up that my company is transitioning our dress code from casual to more of a business casual/modern casual formula. Basically, just when I have built a fabulous wardrobe of denim bottoms (been pairing happily with a dressier top or jacket) we are going to go non-denim in next two months.

I recently purged most of my trousers (they were not getting wear and I wasn't loving any of them anyway ) but have quite a few pencil skirts/several a lines, one pair of black slouchy trousers and a few ankle length colored slacks I can make do with.

Question is: If you were going to build your closet for a non-denim work wardrobe starting nearly from scratch, what would be your priorities? Mostly bottoms - tops are fairly compatible with most bottoms. I need a few new "skirt tops" though.

My only real starting point is knowing I want to find a slim trouser pant - black for sure and some kind of color (cobalt/burgundy/green?) and dark grey.
That seems to be a challenge based on my internet searches.

Thoughts??