so, i’ve been looking at getting some new lenses. i will be headed to asia here in the next few months for a couple of years, and was wondering if it is worth the extra $600 to go ahead and get the faster lenses, the f/2.8?

Specifically, I’ve been checking out the EF 16-35mm f/2.8L or the EF 17-40mm f/4L? What are your thoughts on the two lenses and advantages of the 2.8 that a college grad just couldn’t live without and would be worth the extra $?