i used southwest for my flights.
approx $59 for our flight lax-las, it was quick and easy and painless. southwest has free boarding, meaning anyone can sit anywhere, so we paid for the early bird pass ($10, now increased to $12.50) to be in the first group on board so we got great seats, and i found the price worth it.
southwest, you get first 2 checked bags free (so totally worth it, as that's a savings of $25-75 over other airlines right there) plus your standard carry-on.
for $69 for a flight, 3 pieces of luggage and destination being only 1.5hrs away? totally worthsies for us. ymmv. otherwise i recommend hipmunk. also, it's a short flight, so if any of your flying travellers have reward points with sister airlines in the usa, might be worth cashing in some points for a free flight, as it's so short...
also, if you're looking truly budget, there's a lux bus for only $69 (i think, it's relatively cheap) that does the journey a few times a day between anaheim and vegas, takes about 4.5 hrs and departs 8.45am, arriving 1.15pm (
www.luxbusamerica.com)
i think it would cost more than that to rent a car + gas + insurance, but the driving experience could be fun and might be part of the whole trip experience.