Hi Patrick, and welcome! Gosh, it took a long time for anybody to get back to you on this question.
As far as a small shrub that you can keep trimmed to a size, hibiscus is probably an excellent choice. Pentas are wonderful, and attract butterflies but are a fairly short-lived perennial flower. The tall ones do get to be 3ft. or so, and if you are willing to re-plant them about every 3 years they will look beautiful.
