It's a very personal decision for you whether or not to obtain a passport for yourself as part of your Marine's pre-deployment preparations. To help you make that decision, it's helpful to understand that it would be extremely rare for a family member to travel abroad due to an injury, illness, or other emergency. If the need for a passport did arise, the USMC would assist a family member in obtaining one as quickly as possible.
Passport applications are available at most US Post Office facilities. For additional information from the USPS about obtaining a passport, including fees and a passport application form, please see: www.usps.com/passport.