Craigslist was a great tool for me in my apartment search. Graduating college students are often looking for people to pick up a summer lease, and prices seem really reasonable. I picked the U District, which has its sketchy moments but is overall very accessible. A lot of young people live in Capitol Hill and Ballard, both of which are great locations and easily accessible by bus. I think if I were to move back to Seattle, I would consider Ballard, as there is a great rock-climbing gym there, and I don't necessarily need to be right by campus. At the same time, a lot of graduate students I have met so far seem to live in University Village (just north of UW campus), which seems to be another good hub for young, student types.