Invitations can be mock passports or pretend travel tickets. You could also make an invitation to look like a travel book or spin off of the book Around the World in 80 Days.
Pick some favorite places that the honoree has visited to spotlight with your food, decorations and adult birthday party games.
An easy idea for decorations is to use travel posters of fun and exotic locations that are either favorite destinations or dream destinations. If you have the budget, you could even blow up photos of the birthday person at those locations. A print/copy center can blow up photos to be poster size.
Also, for other activities you might consider special party games and activities that this age group will particularly enjoy.