I am going to buy a Canon 60D to take a school graduation photo and use it for traveling. Is it better to go with the 15-85 or the 18-135+50 header? Do I need to add a header to 15-85?

If you are considering matching these sets, although the grades are different, there will not be much difference in essence. Of course it won't conflict with headers. Comparatively speaking, 15-85 has the best image quality, 18-135 is more affordable, and 18-55 is more suitable for use. A large aperture lens is definitely needed. It is necessary when you need a large aperture in low light indoors, or when you want to develop your own lens sense and composition awareness. It is recommended to go to 50 1.4.