Southwest is the best. Disney world is in Orlando, Florida, But Kissimee is close by and has lots of motels to stay in.
southwest airlines....with one stop in chicago
There is no "best" airline to fly.
Most likely, you'll fly Delta Connection (ExpressJet) from Sacramento to LA and then Delta from LAX to Orlando (MCO)
Disneyworld is in Kissimmee, FL
Alaska Airlines: Sac to Seattle to Orlando.
It might cost a little more, but you can watch satellite TV on all of their flights. You also get all of the free snacks and cookies you want!
I'd definitely fly jetBlue!