Agreed. Unless you have other constraints, go east-to-west. That direction has everything in its favor and nothing against (not even wind).
Weather can be much better E-W and there is generally a lot in favor of that direction.
Also I agree that prevailing winds are not a good reason to go W-E. On the route the OP is proposing it is probably a wash. On the TA I think E-W has an advantage. On the NT I suspect W-E might have an edge wind wise. In any case I don't think that wind should be a major factor in choosing direction of travel for a summer XC tour.
That said I can't agree that there is nothing in favor of W-E. There are quite a few reasons why someone might choose W-E (like we did in 2007). Here are a few reasons why we did:
- We wanted the air travel out of the way up front.
- We think that the Appalachians are the hardest part and wanted to do them when we were a bit road hardened.
- We thought that starting far from home made bailing out harder.
- It was awesome that we finished close to home and were greeted by friends and family at the end.
There are lots of reasons why someone might choose one way or the other.
BTW, I personally would much rather start or finish in the PNW than in San Francisco.