Hi H.,
There are a lot of great preschools in the areas you are looking - one of the main questions I think is if you want a serious Montessori program, or something more open-ended. I polled some of my girlfriends who's kids were already in preschool & asked them what kinds of questions to ask / things to notice as I did my preschool research.
We decided on Calvary Chapel Christian Preschool in Cypress - on Lincoln & Moody. They actually have a private elementary school up through 6th grade, so their preschool classes are pretty academic as well (my son, when he was 3, would get weekly homework). This will be my son's 2nd year there - he started last year when he was 3 years old, and he loved his teacher - it was a great place for him to get acclimated as a first-time-in-school experience. They're also a full daycare, from 6AM - 6PM, I believe. Here is their website:
http://www.calvarycypress.org/index.php?section=1
My daughter is not yet 2 yet, but we will definitely send her there after she is old enough and potty trained.
Their Back-to-School Night will be on Sept. 11, Thursday at 6:45PM, if you wanted to visit - that's what I did - either visit that night, or on an Open House night in the spring to see how the kids / teachers / parents interact with each other.
Hope this helps! Blessings to you & your adorable family - how fun it must be to have twins!