I like a rather simple inside flap to not detract from the top flap.
But I did add a bit more to the inside for embellishments.
Did you enjoy my cards? This particular design is on a CD from the Technique Junkies called Fancy Folds and Motion Paper Crafts. You need to check it out at the Junkies website. It's listed under the Specialty CD drop down menu for $17.95.