OK, to answer the original question...
It's pretty much like anything else with PCS orders. You turn in a preference sheet, they'll try to accomodate you as best they can, depending on how many slots they have at -122 and -106. If you have a really good reason why you have to go to one coast or the other (I'd imagine owning a place is one), they'll go the extra mile to work with you.
As far as which is in more demand? Couldn't tell you... my class will be like the 3rd or 4th which even has the Oceana option, and with only a handful of Navy guys per class, it's hard to gauge interest. I'd personally rather go to VA beach, but if you want to be the one to jump on the grenade and go to Lemoore, I won't talk you out of it
UINavy- are you in the RAG now? I'd love to hear the gouge on how that goes-- big mystery...