The world of California mortgage loans and refinancing your existing mortgage loan is a big world. There are endless amounts of gimmick loans that include interest only loans, and negative amortization loans that I think help people buy overly priced homes at too high of rates.
Many California based loan officers recommend sticking to the traditional 30-year mortgage and refinance when they can afford to. Too many gimmick mortgages leave people with higher interest rates after an initial low interest rate, or charge outrageous fees for pre payment and other such fees.
Some people make the mistake of assuming they can manage a 15-year mortgage. Some people can make the payments barely, but if anything should go wrong they find they are financially strapped. The easier method of going about turning a 30-year mortgage into a 15-year mortgage is to simply double up on the monthly payments every single month.