Lots of touristy things to do in Abilene, Council Grove or Atchison (although probably not the same weekend since they are pretty far apart).
There's ruins of a Pawnee Indian village west of Belleville that's very interesting and Rock City in nearby Minneapolis. Concordia has a few things.
Cottonwood Falls in the flint hills has the Chase County Courthouse, which is cool. West of Hays is Cedar Bluff Reservoir, which has a cool overlook from the top of the bluffs, although you have to take gravel roads to get there.
Also, Lindsborg is fun for Swedish heritage and nearby is Coronado Heights, and lots to do in Salina too.