To really enjoy the island, you have to leave the Trans-Canada and take to the narrow side roads that hug the coastline, winding through seaside resorts and villages, or meander through the countryside past extensive farmlands that grow the famous PEI potatoes.
From the bridge, you can take Highway 2 north to the Malpeque Bay area, through the pretty seaside town of Summerside, and then the North Cape peninsula.
You can take highway 2 all the way back, as it winds over 250 km through Charlottetown and to Souris and East Cape on the opposite end of the island. From Souris, you can catch a 134 km ferry to Iles des la Madelleines (Madgelan Islands), part of Quebec in the middle of the Gulf of St Lawrence.
TIP: The bridge toll is only paid on the way OFF the Island, so if you go east to west, you pay ferry + bridge toll, but if you travel west to east through PEI, you only pay the ferry toll.