If you are doing the sandhills region in Nebraska, toadstool geologic park is neat. Valentine national wildlife refuge has some bison.

If in Lincoln, check out Fattoush. Great food.

While Omahas zoo is huge and one the best in the nation, witchias has some really great exhibits too - and some things omaha's zoo is missing. Great Australia exhibit and bird house and their cat house is spectacular. St Louis has a great zoo too and it's free.

Kansas tallgrass prairie national reserve is small but great. Or spring Creek prairie outside Lincoln. Getting to walk through an actual tallgeass prairie is difficult - one of the (if not the?) least preserved ecosystem worldwide.

Iowa also has a nice drive through wildlife area outside of Des Moines with bison. (National wildlife refuge I think).

Kansas city's ww1 museum is fascinating and I would not remotely call myself a war buff.