I've done both ways in a cab. Something like $15-18 Vs. $30 if you take the tunnel.
Was asked if I wanted to take the "quicker" route along the freeway? last time I was there. Knew it cost a bit more but as my hotel was free and it would be a different viewpoint of the city, I was fine with it.
I still prefer to fly to LAX in order to use the Qantas lounge first