Sensible option: J. Crew, $65 
Splurge option: Saint Laurent, $495
Why dad needs it: Up until recently, your dad took the time to clothe you. Well now it's time you teach your dad about the concept of "slim fit" and wean him off the billowing shirts people mistake for the tablecloths whenever he goes out to a restaurant. Also, dads are prone to rocking garishly bright pieces in the hope of appearing stylish. Let him know that a simple, well-cut white shirt will take care of that every time.