If it's going to be a hauler, I'd suggest Albatross or other upright bars that accept bar-end shifters. Or another option that I like for city bikes is to make it a 5- or 6-speed. I built a mixte for my wife from a Raleigh Marathon frame powdercoated purple: 700c wheels w/ 700 x 32mm Panaracer Pasela tires, stem shifter, Albatross bars, Planet Bike fenders, Wald front basket. She uses it for commuting.
Neal