Welcome to Texas!
First, I'm not a realtor so I have no services to offer except a suggested area for you to look at. :)
My husband and I built in a neighborhood called Cambridge in McKinney. It is a small subdivision -- 109 lots but only approx. 40 or so are built on at this time. Almost every house has children ranging from newborn to 14-15, with the bulk of those in the 5-12 age range. Since there are not a lot of homes built everyone knows everyone and it is extremely family oriented. A group of the ladies walk each morning and we frequently have neighborhood get togethers like scrapbook night, BBQs etc.
The neighborhood has limited entrance and exit points so its a little more secluded but still close to good schools too.
It is located just east of Ridge Road off Virginia Pkwy. and Joplin. Centex builds there and right now has a couple of spec homes for sale. You can also build of course. We just really love this area.
I saw someone mention Castle Hills. This is a very nice area too. It has a lot more homes tho and I know that there have been foundation problems due to the soil they built these homes on. However, if you've never lived in Texas, foundation issues are very common here so don't let it freak you out. The ground just moves so much.
Again, welcome to Texas and good luck in your hunt for the perfect home!