Hey There,
I am a SoCal native. Santa Monica, CA is gorgeous. There are tons of different cultural things to see and do there, with no shortage of preschools for your little girl, as well as restaurants up and down Santa Monica Boulevard for just about every palate.
This having been said, Santa Monica is at least, if not more, expensive that San Francisco, CA. Well, really, all of CA is overpriced, which is why my husband, daughters and I left CA and moved to GA. It was a definite culture shock at first, but we really do like it here now.
Anyhoo....one of the highlights of Santa Monica is the pier, which is just plain cool. There is an amusement park right there that has an old-fashioned ferris wheel and lots of other stuff. There is no shortage of fascinating subjects for people watching. Real estate wise? Probably very little difference between SF and SM. I believe SM has rent control, so if you are renting in SF, maybe you might be able to find something good there, and have the rent controlled.
If you're feeling adventurous, why not take a weekend and visit?
Good luck!
E.