Dakota Dinosaur Museum is a descent size dinosaur museum. There is only one big hall with skeletons and bones. There is a display on how the skeletons are prepared. There are also seasonal exhibitions like minerals and rocks. I would recommend it for small children like 4-5 years old. For bigger kids, it would be kind of small.
The Dakota Dinosaur Museum is quite impressive once you realize that this is one couple's collection of artifacts. In addition to dinosaur bones (some originals and some casts), there is an extensive collection of rocks and minerals and fossils on display.
There are one or two hands-on areas in the lobby and a "children's corner" that consists of some books and posters, but otherwise, this isn't a particularly kid-friendly venue. It is a no-running, quiet-please type of museum, but my kids (8, 6, and 5) still liked seeing the dinosaurs and fossils.
The gift shop does have several children's items.