I agree with valygrl that the Pacific Coast route would be far preferable to coast-coast if you have the 30 day time constraint and are riding unsupported. The direct coast-coast routes have some very long stretches that are remote with few services, and not very interesting scenery. OTOH, the coast route is popular with cycle tourists so there are plenty of lodging and food options, there's a variety of ocean plus mountain scenery almost the whole way, and you're likely to encounter quite a number of other cycling groups and individuals that can also make the trip more interesting. As mentioned, definitely go north to south. The winds can be terrible if you try going north and you also get much better views of the coast when heading south.