We always do a taxi as well, because there are five people in our family, and it just adds up better to take a taxi rather than a shuttle that can often charge per person. Some shuttles will have family rates, but not all.
I like the set up they have at SNA--you just grab your luggage and go out to the taxi lane, and they have either cars or vans all lined up just waiting to drive you to
Disneyland! They know that is where many people who fly in there go,
so they have a well honed taxi system with set rates to Disney.
Good luck,
Lisa