Hello EK. I think that while there are many great towns in the metro west area, Wellesley, Needham, Sherborn and Weston are great towns in which to raise kids. My bias is towards Wellesley or Needham, not only because I live in that area, but because of how I want my kids to grow up. I want them to be in a neighborhood where they can play with the kids on the street, walk to a convenience store and so on. While I do not know exactly what you are looking to find for your children, I hope some of the following is helpful.
Wellesley and Needham have good schools, which is the initial draw for families. Both towns also have neighborhoods so that you get to know your neighbors and kids can play with the other kids on the street. While schools in other towns such as Dover, Sherborn and Weston are also very good, there are fewer traditional neighborhoods because in these towns, minimum lot sizes are generally much larger.
In both Needham and Wellesley, the school districts for the grammar schools are mapped out geographically so that your children become friends with the other children in the immediate area. There are great parks in both towns, particularly in Wellesley, for smaller children. Warren Park on Washington St. in Wellesley is a draw for people from all surrounding towns for its new play structures and its shade in the summer and the sledding hill in the winter. There are family friendly activities sponsored by both towns year round including parades, concerts, street fairs, open houses at fire stations and more. The towns are generally very safe with serious crime being very infrequent (details are readily available from local police departments). Amenities such as quality child care facilities (for working parents) are available as are organized recreational programs (the Y in Needham has great programs and the town of Wellesley offers programs for adults and kids year round ranging from T-Ball to cooking to yoga).
From a practical perspective, both towns offer local shopping areas and several restaurants that are kid friendly, and they are also easy access to larger malls and commercial areas as well (Route 9 in Natick/Framingham and Highland Ave. in Needham are both accessible).
Both towns also offer easy access to Route 128, the Mass Pike and thus to Boston and other areas so that working parents can get back to town for appointments or other engagements without too much difficulty.
Again, I hope that some of the foregoing is helpful. Please let me know if there is any other information in particular that you would like to know. Andrea