One book for you, with all the designs, less than 1250sf, is [ame="http://www.amazon.com/Book-Small-House-Designs-Award-Winning/dp/1579123651/ref=pd_bbs_sr_1/105-6581963-3098063?ie=UTF8&s=books&qid=1185752576&sr=8-1"]The Big Book of Small House Designs[/ame]. Another is [ame="http://www.amazon.com/Good-House-Cheap-Adventures-Extraordinary/dp/1561587524/ref=pd_sim_b_3_img/105-6581963-3098063?ie=UTF8&qid=1185752576&sr=8-1"]Good House Cheap House: Adventures in Creating an Extraordinary Home at an Everyday Price [/ame]
Some designs are quite impressive. Remember that our population is aging and they will not be able to handle stairs as easily as younger people. Nor, will many want to be so spread out with only one or two people in the house. Insurance in the coastal areas will also push people to smaller homes, less expensive to replace. There are green aspects to smaller tighter homes, too. I've often said that a community calling itself green needs to be sure to keep the homes small, especially if the homes are empty much of the time.