I have two beautiful Mezuzot in my possession. It seems obvious that I affix one on the doorpost of our new home's front entrance. What would be the most appropriate room inside the home to affix the second Mezuzah?
First, Mazel tov on your new home!
A rabbi once told me that the order should be: outside doors, then bedrooms, then dining room, then living room, then kitchen. I don't have sources on this, but here's a list of all rooms that biblically require a mezuzah: http://www.mezuzadepot.com/tag/rooms-that-require-a-mezuzah/
- Entrance into a house
- dining room
- living room / den / family room
- office / study
- attached garage. This includes the large sliding garage door.
EDIT: Per DoubleAA's comment, there are exceptions to these.
They are not biblically required if the doorway does not have a lintel (top part), and two side posts, the room is smaller than 64 sq. ft. or is a:
- room used exclusively for business
- a beit midrash
- used for exit only, like emergency exits or fire escapes
- room without a roof
- doorway less than 36″ high
- door that is sealed shut
Per Sefer Lekach Chaim if someone can not afford to purchase a Mezuza for every door that requires one he should first place on the doors that are Biblically obligated in Mezuza (as opposed to rabbinically obligated).
כשאין ידו משגת לקנות לכל חדרי הבית
מי שאין ידו משגת לקנות מזוזות לכל חדרי הבית אלא רק למקצתם, יקבע המזוזות קודם בחדרים שחיובם מן התורה ואח"כ בשאר החדרים, וכן מי שאין לו אלא מזוזה אחת יקבע המזוזה בפתח הבית, וכן מי שיש לו חדר בתוך חדר ואין לו אלא מזוזה אחת, יניח המזוזה בפתח החדר החיצוני
In general all doorways to rooms of 36 square feet in a Jewish home that are used for living (to exclude bathrooms and closets) that have both a lintel and a right doorpost as one is entering the doorway should have mezuzot affixed to them. As is common in Jewish law, there are a number of different opinions about certain details regarding which doorways are obligated, so if you only have one mezuzah available, I would recommend choosing a doorway with the additional features of having a left doorpost, having a door attached and opening to a room of 64 square feet that is no less than 6 (or ideally 8) feet in either dimension.