I agree with some of the posters here that have touched more on the personal note rather than the physical structure itself.
Not having children and any immediate family in the area does lend a few helpful points. I am also assuming the subject has been discussed in great detail with your wife.
But as mentioned by others. Working from home takes a great amount of discipline on both sides of the spectrum. You need to ponder greatly on your personal ability to not only work when other matters may distract you. But also on your ability to set the work aside when needed.
It becomes much more tempting, when working from home, to procrastinate or not work at all when you should be. On the flip side, it also becomes easier to work To Much and ignore personal matters that need time and attention. It can be a very fine line to walk.
If on a cold, rainy, not feeling so good day will talk you out of working and curling up on the couch when you should be in your home office you maybe should rethink your ideals. Also, if you are more the other spectrum and find yourself eating dinner in front of your computer or working late nights just to finish that project up early, you may need to rethink it too.
Work is work, and in my lifetime I have watched many friends and family pass away. Most said things like... I wish I would have spent more time with my friends, family or doing things I loved. Never have I heard one say... I wish I would have worked harder.
Make sure, if you do go the home office route that you have the ability to put the work down. Eat dinner with your wife. Still make time to do the things you enjoy and remember the work will always be there when you come back.
Lastly, Get a seperate business phone line and a P.O. Box. Use these for all your work related letter heads, listings and such. This helps keep random people from knocking on your door and allows you the ability to tell yourself that you will not answer the business line late hours, Sunday's or times that you devote to yourself, family and more.
Good Luck!