In a double boiler, melt the chocolate chips. Dip the tips of the pretzel rods in the chocolate and place upright in a glass in the freezer for 1 hour. Set the remaining melted chocolate aside.
Combine the vanilla extract and whipped topping. For each float, place 2 scoops of ice cream into tall float glass. Add 6 ounces root beer and 6 ounces cream soda to each glass. Top with the vanilla-flavored whipped topping. Remove pretzel rods from freezer and place in Root Beer Float. Garnish with extra drizzle of melted chocolate and serve immediately.