Wear your sneakers. Honestly, depending on how much work you plan on putting in, you may want to consider wearing athletic gear. The Center is connected to a system of tunnels that can either lead you down to the metro or to other shopping locations. It's a lot to see in one day, to buy in one day, but it's way worth the trip. Like the rest of Montreal, there are plenty of food offerings in the food court and a lot to choose from. You may consider doing this trip and all of its connected shopping venues in two days.