We have found very cheap non-stop flights from Philadelphia to Las Vegas for only $80 return with US Airways.
This is also a great flight for a mileage run!!
Las Vegas, USA
Very good availability from January to February 2015
21st, 23rd, 24th, 25th, 26th, 28th Jan
1st, 2nd, 3rd, 4th Feb
30th, 31st Jan
4th, 6th, 7th, 10th Feb