Effigy Mounds and Pike's Peak State Peak are fine especially for hikers. Spook Cave, on the other hand, sucked. If I remember properly there was a true cave on the other side of the Mississippi.
Another vote for the Grotto in West Bend ... the pic doesn't really do it justice - its impressive to see.
Also, you Lansing folks (I didn't know people actually had computers up there) - Has anyone ever stopped at Effegy Mounds? I thought about taking a day trip with the wife to hike the trail - is it worth the time? Maybe check out Spook Cave while were at it... do either of these suck?
Oh, and a shout out to Dubuque. You used to suck something fierce - but the area down by the river is pretty cool now with the aquarium / Grand harbor / casino / and the best resturant I've been to in a long time the Star Brewery.