I highly recommend the Heritage Trail driving tour. We picked up a free CD from somewhere in Goshen - can't remember where - maybe the Chamber of Commerce? We did the drive over 2 different days, and thought that it was extremely well done - very informative, and took us to areas that we would not have gone to otherwise. Now I can't wait to go back to Wakarusa to get more giant jelly beans!
We also very much enjoyed the Menno-Hof Mennonite-Amish Museum. Quite a nice museum and gift store. It helped us understand the similarities and differences between the various religions and also understand their beginnings. (And I'm not normally a museum person!)