Another book by James Howe that you may enjoy is The Misfits. The book is about four students who do not fit in at their small-town middle school and decide to create a third party for the student council elections to represent all students who have ever been called names.
Romance and lust and family dynamics feature prominently in "Rococo" by Adriana Trigiani. Some other titles that you might like:
Garden Spells by Sarah Addison Allen
The women of the Waverley family -- whether they like it or not -- are heirs to an unusual legacy... (B)ehind their Queen Anne home on Pendland Street in Bascom, North Carolina...an apple tree bearing fruit of magical properties looms over a garden filled with herbs and edible flowers that possess the power to affect in curious ways anyone who eats them. (from Barnes & Noble)
"An Unpardonable Crime" by Andrew Taylor best fits into the category of literary mysteries in a historical setting. This is a genre that I personally enjoy reading, especially if a real person from history is featured in the story. Here are some other good titles in this genre.
If you liked Message in a Bottle by Nicholas Sparks, how about trying:
Bridges of Madison County by Robert James Waller When Robert Kincaid and Francesca Johnson meet, magic happens. Kincaid, 52, a photographer for National Geographic, a mystical traveler of faraway land, feels out of harmony with his time. Francesca, 45, once a young war bride from Italy, nurses her childhood dreams. --catalog summary
To Kill A Mockingbird is one of my all-time favorites too. I do believe that it is one of those books in a class by itself - there really isn't anything else that comes close to it! Having said that, I do have a couple of suggestions for you. Some of these titles deal with race relations; others deal with growing up in the South. Hopefully you will find something here that you will enjoy.
Black and White by Paul Volponi
Three teenage friends confront racism during the summer of 1955 in a small Southern town.