Maybe it's just because I am of Irish-German descent, but I would question carrying just two ounces of sunscreen, especially through sections of the desert and the Sierras.
Perhaps you are used to the sun (you are a resident of the Southwest after all), but I am fairly sun sensitive and will generally carry extra sunscreen if conditions merit. And if you are traveling across snow in the Sierras (a fairly likely occurrence if you are a north bounder on the PCT), you will have quite a bit of reflection off the snow.
On your tent...it's a bit of work to setup and considerably heavier than other options, but at the same time its robust structure makes site selection less critical.
Other thoughts...I can speak to the Washington section of the hike...Depending on the time of year you reach Washington, your weather experience can and will vary. We had early and heavy snow last year, with quite a bit of snow in the mountains in late September/early October. If you are quick and plan to be finished in August, the weather in Washington should be rather good. September is probably my favorite hiking season because of the change in the color of foliage(and appreciable lack of bugs) but the days get considerably shorter and it gets colder. Some Septembers are warm and relatively dry, some are cold and wet.
The difference in temperature isn't as big of an issue as the difference in humidity. There is a tremendous difference, in my humble opinion, between a 40 degree day in Arizona or Utah and a 40 degree day in Washington. The Southwest as you well know is very dry. The Northwest tends to be under clouds a lot of the time and thus the air contains quite a bit of humidity by comparison. It can make 40 degrees feel considerably colder and more clammy. And if you get one of those classic week-long rain spells in the Northwest, it can be pretty miserable to be on the trail sometimes.
Simply, I would take this into account especially if you think your hike will take you into mid-September or later.
Anyhow, best of luck on your 2009 thru-hike. I hope to see you out there!