I moved to Vegas 2 years ago. Wife, 2 kids (14 & 11)...
We bought a house in Summerlin. Also like Green Valley if you want to be in more of a yuppy neighborhood (lot's of restaurants, shopping, etc)...but along with that comes a little more hustle/bustle. This area is East of the strip.
To go on the more quite side of Vegas....go west young man! Summerlin is great. And for all the "local" casinos in Vegas....the Red Rock is the best by a lot. It's a little more expensive to live in Summerlin, but worth it, IMO.
Really depends on what your looking for. How old you are? Kids? Where do you work?
A lot of people will say Southwest is cool.....and it is. A newer community that will someday have a school, and library, and shopping, etc.. Problem for me is I have teenage (more/less) kids and didn't want to see the place develope over 10 years. I wanted it now!
The houses in Southwest are big, beautiful...with backyards so small you couldn't put a pool in (which is why I didn't move there). If that's not an issue, then Southwest is pretty good bang for your buck. Check out Mountains Edge on the internet to get a feel....
Bottom line....it really depends on your situation. Good luck!