I also recommend the I-8 route east, then north along the Salton Sea. Interstate 15 almost always has heavy traffic, and that's compounded by the never-ending Caltrans construction projects. BTW the hang gliding area the other person mentioned is in Pine Valley, just off I-8 as you pass Alpine heading east.
Have fun with your drive; make it leisurely and enjoy the beautiful mountain & desert scenery. :-)
[B]BichonLover is a 100% California gal, driving a vintage Fleetwood in SoCal.