If you're going to see just one dance performance while you're in town, make it Hubbard Street. Chicago's best-known dance troupe mixes jazz, modern, ballet, and theater dance into an exhilarating experience. Sometimes whimsical, sometimes romantic, the crowd-pleasing 22-member ensemble incorporates a range of dance traditions, from Kevin O'Day to Twyla Tharp, who has choreographed pieces exclusively for Hubbard Street. Although the troupe spends most of the year touring, it has regular 2- to 3-week Chicago engagements in the fall and spring. In the summer, the dancers often perform at Ravinia Festival, the Chicago Symphony Orchestra's lovely outdoor pavilion in north-suburban Highland Park.