For him: Jack's standard go-to is a dark suit with a light shirt and striped tie. You'll also want to have a glass of scotch handy.
For her: You'll want to wear your Converse sneakers (Liz has to do a lot of running around) with jeans and a smart and sophisticated blazer. But Liz's glasses are the pièce de résistance. Get them right, and the rest of the costume is easy.