I have to agree with Jeremy, it's not easy to locate property based upon it's archetectural style. Lucily, Spanish sylte homes are plentyful in Southern California, so you shouldn't have too much trouble locating them on the MLS> Craftsman, on the other hand seem to be located together, in certain older neighborhoods. In Los Angeles area that would be Venice,Inglewood, and some pockets of Larchmont, and WLA.
I would sugest the older areas of Ontario, as a place to start. Access the MLS with no obligation from my website below.
There are not any "neighborhoods", or areas that have only Spanish Style homes, but there are communities in Southwest Riverside County that have "Custom Homes". Real Estaete sites are not really that detailed in their search criteria.
It's alwasy best to work with an agent who does day to day full time Real Estate business, in the local area you are interested in. Good Luck.
Prudential California Realty