Ted; You're right, timing is important. You have hurricane seasons on both coasts, the winter trades in the Caribbean, the rainy season in Panama, plus you have to leave enough time to enjoy the trip.
We've done the Seattle to San Diego trip twice. This last time we stopped everyday pretty much. The first time Vancouver Island to San Fran non stop. Check the archives for the West Coast legs. A several forum members have done it recently and going in your direction.