It depends on the sun intensity and light exposure. If the window faces South in hot direct sun: succulents, Kalanchoe, and cactus are best. Look for flowering varietals. In moderate climate areas: African Violets, anthuriums, and orchids would be good. East or Northen exposure would be for lower light cyclamen, gloxinia, begonias, and bromelliads. Air flow is important as is humidity when needed. A saucer of gravel w/ water under a plant provides addt'l humidity as long as the soil is not sitting in standing water.