I really gotta say, with the time frame, Would be a good time to start in the north. or hell, even hitting up southern Oregon, going to Grants pass (which, by all means, is a shit hole), and heading south. Late spring is a great time to be in the forest, should be warm enough to camp out, and take your time heading south.
Hard to say if its better taking the coast, or inland for the north, both have their perks, but once you get central (SanFrancisco), I would say to head to the coast.
Santa Cruz is a pretty friendly city, easy to get into the hills and camp, and from there you can easily hitch down the coast through Big Sur, (try to sneak into the Esalen institue, great bath houses on the ocean) enjoy the hotsprings and pretty much unlimited hiking and camping possibilities.
From there getting to LA is no problem, and further to Sandiego, then out to the slabs for the end of the year. Slab city is fucking great, but summer is hell. Meet up with SPAZ and Digihitch around New Years, say hi to Moth from me, and enjoy-
Need any contacts or advice along the way drop me a line