Since this is a basic biscotti recipe here are variations.
Dried fruit: Apple pieces, craisins, fig,
Nuts: Almonds, pistachio, walnuts
Spices: Cinnamon, nutmeg, pumpkin spice
Extracts: Almond, lemon, orange
Chocolate: Melt the chocolate and dip the biscotti or mix in chocolate chips.
A Note about adding other ingredients:
A good starting point when adding spices is with one teaspoon.
When adding dried fruit or nuts a good amount is 1/4 cup.
Adding additional extracts start with 1/4 to 1/2 teaspoon.