For family living the nicest areas are indeed Henderson and Summerlin. Personally I live in a master planned community called Peccole Ranch, which borders Summerlin. In my opinion the west side, where I live, is better because:
It has an Orange County, California, look and feel to while much of Henderson looks like it was made from a cookie cutter.
The west side is higher in elevation and thus cooler in summer.
Henderson suffers from the noise of landing airplanes.
The west side is right next to the mountains, which offer outstanding hiking and climbing.
The future growth of the west side seems to be better planned.
If you ask someone from Henderson they will claim Henderson has less traffic, but there are two sides to that issue, and I think the west side is better in that area too. I’m sure I will hear from somebody from Henderson over this, and am happy to print a rebuttal in the future, because I believe in presenting both sides.
The worst parts of Vegas are around downtown, gradually getting better as you move further away. For something in the middle there is lots of growth on the south side of town along the I-15 and the north side along the U.S. 95.