My youngest son recently was invited to a birthday party for a 13 year old girl. Invited guests included young men and young ladies from as young as 9 years to as old as 17 years. However, the party was a huge hit and everybody participated fully in the celebration, because it was an activity-based party. In this case, the party was held at a skating rink, and everybody was able to enjoy themselves on the ice. Other options that engage guests of all genders and ages would include paintball or laser tag, karaoke, Dance Dance Revolution, or even a pool party.
Remember, take advantage of the opportunity to be creative in your party planning and have a great time doing it!