As to California, the reason the haha leaves in November is that's the end of the hurricane season in Mexico. IIRC, it starts up again around June, so your January to April time frame would work out well there. Then the rest of the year it could be chartered in California, north of the hurricane issues.
Also, I agree with Cruising Dad, seriously look at whether or not you could do this without chartering the boat out. Living on the boat 4 months a year, your going to want to be able to do little customizations to make you life easier which might not work so well on a chartered boat, and having lots of your own stuff on board all the time will make it feel more like home and less like a hotel. Not that it couldn't be done, perhaps this is the right choice for you and I'm sure others do it this way and love it, but for me I would rather buy a cheaper boat that could be all mine then a nicer boat I have to share
As to which is better, California or Florida, I have sailed neither yet, but Florida / Bahamas would be awfully tempting. It may also be possible to start on the east coast, then in a few years truck it to the west coast for a change of pace. (I guess that might depend on the size of the boat.) Seems like if you sailed to Texas one year and had it trucked over to the sea of Cortez, it might not be too outrageous of a price, but again, I am talking about something I know nothing about!