Chicago's motto, which means "City in a Garden," is most apt in spring or summer (or early fall). If you plan to visit in winter, be prepared for something a lot more like "City in a Blizzard." This "Urbs in Hortis” itinerary will lead you through the most garden-like aspects of Chicago's city life, which at temperate times of year are truly delightful.
Day One: First, enjoy an espresso drink at one of the coffee shops or bakeries in the Near North, and pick up some edibles for a picnic lunch. Then proceed to Bike Chicago on Navy Pier, where you can rent a bike for about $35 a day (if you've brought your own, even better). Ride along the lake up to Lincoln Park, the Chicago Park District's prized possession. The Oak Street Beach, at the south end of Lincoln Park, is a great place at least to wiggle your toes in the water -- or in summer, go for an all-out swim.
Lincoln Park's two main attractions are the zoo and the conservatory. The Lincoln Park Zoo is actually Chicago's second most popular attraction overall (after Navy Pier). Don't miss the primates, penguins, or the Regenstein African Journey. Both the zoo and the conservatory are open from 9-to-5 daily, and are free. The conservatory is a three-acre garden under glass, with many tropical plants represented. The landscaping in Lincoln Park also lives up to the "Urbs in Hortis” motto whenever possible weather-wise.
After returning your bike, make your way west to Michigan Avenue on foot. The wedding-cake-like Wrigley Building (on Michigan Avenue, a block south of Illinois Street) has a beautiful courtyard, which makes a perfect place to stop and rest for a while. Then walk up Michigan Avenue to the John Hancock Center, where you can enjoy the city's atmosphere outdoors on the 94th floor, on the screened observatory deck (open 9 AM to 11 PM). Have dinner on the Magnificent Mile and get a good night's sleep, for more garden walks on day two.
Day Two: Today, walk or cycle south through Grant Park, enjoying the Wildflower Works, Buckingham Fountain, and the Rose Gardens. Grant Park also has numerous tennis courts and baseball fields. When you reach the Museum Campus, choose either the Aquarium or the Field Museum in which to spend a few amazing hours. Then cycle down Lake Shore Drive, or take the Metra train south from Roosevelt Road Station to 59th Street Station, to the University of Chicago. Have lunch at one of the college-y eateries on 57th Street, and then tour Frank Lloyd Wright’s famous Robie House before tours stop at 3:30. Explore the University of Chicago campus’ quiet, arboretum-like atmosphere and Gothic architecture before heading back north to downtown Chicago.