I commute PDX-SFO every two weeks or so and have been doing this for 10 years. What I've learned
- I usually wait to buy my tickets until I'm fairly certain that the trip will happen as planned; I usually know 2-3 weeks in advance
- All it takes is one or two trips to be hosed and I've completely lost any advantage of advance purchase because with change fees etc, I'm often in better shape throwing away the ticket
- I stick with UA due to my international travel, but I'm 30K away from hitting Million Miler status and I'll likely move over to AS at that time due to better overall schedules
- If I were flying on my own dime and or if SJC were an option (its not, I work in SF), I'd seriously consider WN just due to the significantly more flexible travel options for making changes