Gingerbread Lane and Frosty Circle is one of my favorite free places to see holiday light displays. It's nice to drive through, but even better to walk. The organizers recommended visiting between 5:30-9:30 pm and parking on SE 8th St, if you plan to walk.
Gingerbread Lane is on SE Richland Ct and has a one-way route, which allows you to read the story boards. All 31 houses participate. It's a free event, but at the end of the route they welcome food and cash donations for The Food Bank of Iowa.
Across the street on SE Rio Cir is Frosty Circle. Unlike Gingerbread Lane, not every house participates but it's still worth your time to see both. This year, only two houses aren't participating.