I rarely fly out of T3 at McCarran but the few times I have it has been a great experience. To start off the terminal is new, modern, open and airy. There is lots of room everywhere, from the departures drop off to the ticket counters to the gates, it never feels crowded.
We had TSA pre-check and it was a breeze. Not one single person in line! We were through security in probably 2-3 minutes. T3 has many restaurant options ranging from fast food like Carls JR and Burger King to the higher end Las Vegas Chophouse. I personally like the La Tapenade Mediterranean cafe which has a large selection of salads, paninis, wraps and desserts.
Flying out of T3 at McCarran was a real joy and I look forward to my next flight out of there.