What is the best location in Assisi to stay? I like to be in the town center with sites, restaurants, shops within walking distance.
Assisi is not a very big town, about 1km end to end. Stay in the town center and you will be fine.
Stay near Piazza del Commune. That's the main piazza. (I hope your legs are in good shape. In addition to being beautiful, Assisi is very hilly.)