There really isn't much in Iowa. Our state parks stink. Wildcat Den is decent, and it's a quick drive to Muscatine. Effigy Mounds has one long trail that is good. I would like to suggest going on line and getting a state park pass from the Wisconsin DNR and you can make a day trip, or a weekend trip out of drives to Platteville, Madison, or PDC. Governor Dodge by Platteville is 5000 acres. Not strenuous, but there are some good, well maintained trails. A few miles up 151 is Blue Mound. It's smaller, but has some nice trails. Spend the night in Platteville if you like. Devil's Lake is an excellent park north of Madison. It has a bit of a murder problem, but the trails are excellent. As posted, the last time Mrs. Lucas and I were there a hiker was murdered about 1/2 mile up the trail from us. The killer is still on the loose. Around the area are a few more state parks, and the House on the Rock, and the Frank Lloyd Wright site, Taliesin. It's certainly picturesque. Around PDC or La Crosse there are multiple large parks with good hiking. PDC could be a day trip. The park there is Wyalusing, and it is a very large park with quite a few trails.
If you fancy a drive to Illinois Starved Rock is 2 hours from IC, and the trails have some challenging spots, and you get a lot of good views of the Illinois River. Another day trip option is Siloam Springs by Quincy. I have heard good things about Mississippi Palisades over by Savannah, IL.
Pere Marquette is another good weekend trip option. Very good hiking that can be spread over two days, and there is a lodge on the park grounds. Indiana has several weekend trip options that can easily be accessed from the IC area. Turkey Run has a nice lodge, and it's just a few miles inside the Indiana line off of I-74.