No visit to Umbria is complete without a visit to Assisi. No matter what your religious leanings, the words of peace and simplicity preached by St. Francis still inspire pilgrims today.
The first stop when visiting Assisi should be in Santa Maria degli Angeli, just below Assisi. It was here that St. Francis founded his order, and the tiny chapel he used in now housed within the larger SM degli Angeli church. This is an impressive church in it's own right and probably gets overlooked. If you get a chance, stop in sometime before you drive up into Assisi.
Assisi is a charming town all on it's own, and the Basilica is just the icing on the cake! There's the upper church, the lower chuch, and the crypt, where St Francis himself is buried. There's nary a hint of the earthquake damage from 1997, and the richness of the frescoes is almost overwhelming.
In addition to the basilca there are other churches worth visiting - Santa Clara, and San Ruffino, where Francis was baptized are two must sees.
In the Basilica you can use headphones (available outside the church, €5 dontation) to hear all the details, and this, combined with the headsets now used by all the tour groups makes the church much quieter and peaceful.
Assisi is another city I never get tired of visiting - there are always unexplored side streets and hidden treasures to be found.