Some of this will depend upon how long you are going to be living in Califorina or if you are planning to get a job while you are there, but don't forget to investigate the legal issues involved.

Assuming you are Canadian citizens, you will need permission to work in the US, and depending upon the length of your planned stay, you might also need to get a visa beyond what a typical tourist gets.

I'm not sure what you'll need exactly, but I would make sure to include some research with the US Immigration Dept. as you start your planning.