I'm late in responding to this so I don't know how helpful my advice will be.
I currently live in Simi and have also lived in Thousand Oaks. I prefer Thousand Oaks. It's cleaner, more well-kept, has more tress and also it stays about 5-10 degrees cooler (I don't like the heat). Thousand Oaks also has a Whole Foods and a better farmers market (not that the drive is a big deal from Simi, but I don't like having to drive much if I can avoid it).
When I first moved to California 11 years ago, we moved into the apartments in Wood Ranch. It is a nicer area of Simi Valley and there was nothing to complain about. It is very close to the 23 Freeway which means it's fast and easy to get to Thousand Oaks, Malibu, Ventura area.
We moved from Wood Ranch into the Knolls in Thousand Oaks. I liked those apartments and the area a lot more than Wood Ranch. The Knolls is close to nice parks, walking distance to a shopping center with groceries, Starbucks and restaurants. It is also very close to a very nice shopping center (on Westlake Blvd, called Westlake Promanade) with a theater and restaurant and shopping. It is also only a few miles from two different Trader Joe's locations and only a short drive to Whole Foods and the farmers market and a large, nice mall.
Alas, now we're back in Simi. It's fine but I don't love it. Simi is a little bit cheaper than Thousand Oaks, but for good reason in my opinion.
I also have a 4 year old but we are planning on homeschooling so haven't looked at preschools. I know I have seen a sign for Montessori schools around here though. Sorry I'm not much help there.
Good luck, and if you need any more help, let me know!