This article offers excellent tips for new home owners. It also points out interesting effects of buying lamps and vases in pairs.
http://interiordec.about.com/b/2010/03/11/how-to-choose-versatile-furnishings-for-your-home-3.htm
Here are tips on how to make your home feel serene and peaceful, so that you’d say “Ahhh…” everyday when you come home.
http://www.shelterpop.com/2010/03/11/decor-by-mood-serene/
We also recommend adding some Zen Asian decor or soothing water fountains to the final touch. Ahhh….!!! 
This is a good article from About.com about great gift ideas for new homes. The author recommends giving dramatic vases and table top water fountains among other gifts.
We’d also like to suggest Christian gifts or inspirational decorative crosses if you know the home owner is religious. Other home gifts you should also look into would be intricate wall decor and playful wind chimes.
Happy housewarming gift hunting!
http://interiordec.about.com/od/movingtips/a/housewarmingift.htm