Daylilies are great, no-hassle flowers. The original orange hemerocallis fulva are sometimes known as "ditch lilies", because they, well, happily grow in ditches. So, as long as they have some sun (they grow fine in shade, but don't flower much), daylilies are good!
Individual flowers bloom only for a short while (hence the name), but most daylilies are prolific, sending up many flowers, so an individual plant will usually bloom for several weeks. Combine a few kinds together, and you can have several months of blooming pleasure.
Daylilies were introduced into Europe from Asia over 400 years ago, and there are now more than 80,000 recognized cultivars in nearly every color and adapted to nearly every sort of climate, even Chicagoland.