I am writing to let you all know that I will be leaving _______________ at the end of the month. Due to the arrival of my first child, I have decided to accept an offer from a company that is located only minutes from my home. Over these past two years I have enjoyed working with all of you, and although I will not miss the long commute, I will definitely miss being a part of such a great company. Thank you for your understanding and support. Best wishes to each of you on your current and future endeavors.
(YOUR NAME HERE)