If you’re heading past Dubuque and into Iowa, the Mines of Spain Recreational Area is a great stop-off to stretch your legs. It offers a wonderful vista of the Mississippi River, along with many pleasant, winding paths to hike on. There’s plenty of wildlife too; we’ve yet to visit and not see at least one otter or woodchuck. Do be sure to wear bug repellent, we’ve had a major tick run-in in the past.
Mines of Spain Site and Maps (at bit confusing on a google map as much of the park doesn’t appear as parkland)