Carnegie Mellon or Stanford
krishna2: Both are GREAT schools and consider yourself lucky to have a choice. I did my masters at CMU (and have lived in Pittsburgh for 4 years) but for the past 8+ years have been in the bay area.The cost of living is very very cheap in Pitt, no doubt.
Personally, I like having four different seasons - so weather was not a big deal for me. If you want consistent weather and clear blue skies, palo alto, it is. YMMV.In CMU, you are very close to a whole lot of other big cities and universities - so travelling is lot easier.So all that said, now to the important part: the important decision will be based on what your interests are.
CMU is very strong in Robotics and Artificial Intelligence
fields of study. Similarly, Stanford has its big specialties as well. So if you already know that you might major in Computer Science, try looking at the profiles and research interests of the computer science faculty at each school. Give yourself as much flexibility as possible here, because what you think/know now will be lot different in 2 years, 4 years and 6 years from now.If you are entrepreneurial and you want to do a start up, then just close the circuit and take the shortest path - the bay area.Or if you still want to do that, but take the road less taken, come here via CMU.In anycase, read Robert Frost's "Road less travelled" poem. :)Good luck.