well I must say that JParrott has perhaps posted a perfect response in how to craft a great bar inventory (I have made a mental note to add one or two of the suggestions that I am missing).
Having said that....I will add my 2 cents on just a few things:
Stay away from Montgomery County as well.......stick to good liquor stores in DC (no full disclosure required as I live in Bethesda).
I would consider adding Ameretto, Limoncello, and Baily's. I don't drink Baily's, but I get asked for it by guests quite often.
I have 5 or 6 bourbon's on hand...but Eagle Rare is my (current) favorite amongst them.
I also have a nice sherry and LBV port within my bar as well.
Good luck and have fun!