The Tall Grass Trail is a beautiful "hike" (really more of a walk...) through a wonderfully restored tall grass prairie. Very easy trail --- completely paved --- and appropriate for families with young children. We had our toddler and infant in tow and everyone enjoyed. Also make sure to stop by the learning center --- truly a hidden gem in rural Iowa.
Neal Smith Wildlife Refuge has 3 trails: Prairie Overlook Trail (1/2 mile), Tallgrass Trail (2 miles), and the Savana Study Area & Trail (not sure of distance). I took the Tallgrass Trail. By the time you get to the trailhead and at the end of the hike get back to the parking lot, you'll have walked 3 miles. There are several declines and inclines, but they are all gradual. Good paved trail with nice benches every 1/4-1/2 mile to sit and rest or enjoy the sounds of the birds. No pets are allowed on the trails. Really enjoyable walk!
there is a second loop that is through savanna. It is a 1 mile loop of crushed limestone. It is a great trail for children. It is short and sweet with enough to see and enough grade challenge to make it interesting. There are also plenty of benches for rests. Highly recommended.