With kids, don’t worry about seeing everything in the museum, just spend time in the areas they find interesting. It may be a Miro painting, the jellyfish, stegosaurus bones, or an upside down prop-plane. Often a museum visit makes for great dinner conversation, and may spark a special trip to the library for books on a subject or even inspire an art project.
Free outdoor concerts are a wonderful gift that come with nicer weather. Millennium Park offers lots of free concerts- great for picnic dinners. Old Town School of Folk Music offers free children’s concerts in the summer mornings in Millennium Park. And many of the Chicago Parks have free concerts throughout the summer featuring a very wide range of musical styles.
Old paper towel rolls transform into a number of pretend instruments and for older children chop sticks work well for drumsticks or a conducting baton. An inspired 'musical performance' can continue for days after- sometimes weeks.
Be sure to check with the museums, city and parks around where you live for free opportunities and get inspired!