What line of work are you in? St Johns may be limited in that respect. What you save in rent may be eaten up in time & transportation.
Portland has two youth hostels, each with a 3 day limit as far as I know. Division is the major artery south of Hawthorne. Rents should be cheaper in that area. Belmont, to the north, is getting some of the more popular Hawthorne spill-over. The Hawthorne IYH should be your base for checking out the area between Division & Belmont, both of which are convenient to Hawthorne.
The # 17 Trimet bus runs right by the NW IYH, already mentioned, if you want to job shop in the downtown core. Due to a recent change in administration, the school system is in a state of flux. Some schools now open may soon be closed. Capitol Hill, aka Multnomah Village, on the # 44 bus line is a nice little self-contained community. It might be worth checking out in that respect.
You are smart to plan this far ahead. Even if you plan on driving, I suggest learning to navigate via http://trimet.org/ while you have the time. Following behind a # 4 bus, for instance, will get you to Division Street; # 15 to Belmont, etc.


