Love megabus! Where else can you find such cheap transportation? Every six months I book my father a bus trip out to Las Vegas from Riverside. If you book it six weeks in advance you can get it super cheap. And when I say cheap, I mean cheap. Twice I've booked him his trip out here for less than five bucks round trip. Can you believe it?! The most expensive I've ever booked it was 25 each way which ultimately cost me 50 bucks. Thats still a good price in my opinion.
The double decker bus is large, has a bathroom, has free wifi, nice cold air conditioning, and heat. It's never overly crowded which tells me that its still cureently one of the best kept transportation secrets.
From Las Vegas it also goes to Los Angeles. So if you would like to go there instead of riverside you can, for the same price. Give mega bus a try I can't see it being disappointing.