Fares from LA and SF to Las Vegas definitely show the effects of Spirit's presence. I wish Spirit would fly SF area to LAX, but I think they realize that Southwest would defend that market to the death.
I am not sure I agree. I belive that NK has cut their OAK -LAS flights from 3x daily to 2x, and the flight times are pretty poor. From OAK at 6am and 1400, from LAS at 11:45am and 22:00.
WN has 7x non-stops from OAK to LAS. I didn't bother counting SFO and SJC.
I did a mock booking for 8-jan. I can get a seat on NK for $35, where WN is $104, but I like WN, and if I were to *really* fly NK it would cost me $79 (carry on and seat assignment). Notice how the price doubled there.