It really depends on the lot..

size. If you have a sizable lot, you should build a two story house which is cheaper and save some space. Plus, you may be able to capture the view and have more privacy. You should also look into the grading of the lot. Is it upslope/down slope? Another thing you need to consider is age and parents/in-laws. Are they gonna stay with you? One more: Look into some Feng Shui books too, to give you some ideas on locations and directions of the house.
Good luck!