The West Des Moines Library has a fun play area and a Storywalk that leads to Ashawa Park. The Tale Trail, as it's known, starts behind the library and is approximately a 1/2 mile round-trip on a paved trail and through a tunnel. The current book is Bess The Barn Stands Strong, which my son enjoyed.
There's also a 1/2 mile paved loop trail around the pond. Along the trail and across from the library is the Jamie Hurd Amphitheater and the location of the public artwork Progression.
The children's play area inside the library has a light wall, magnetic tiles, Lego Duplo table, train table, puppets, puzzles and a pretend play area. The library also has a used book section, with hardcover children's books priced at $1 and paperbacks at 50 cents.