Briefly, taking a shared van (shuttle bus) like Prime Time Shuttles (http://redvans.com) or super shuttle (http://supershuttle.com)) will cost about the same as taking the Disneyland Express Bus (http://airportbus.com) ($25-$30 per person, ROUND TRIP OR $50 to $60 each way for all of you.). Here are the details:
1. For the van, when you arrive, you go to the area outside your terminal that has the ORANGE overhead sign saying: "Shared Ride Vans". You will be put on the next van to Anaheim (which may or may not be waiting). If it is waiting, it may or may not have enough empty seats for all of you. If it does, it might attempt to fill up before leaving the airport. (This may cause some delays). The ride is about 40 minutes but plan on it taking about 1-1/2 hours all together as you may have to wait while others are dropped off first. It's unlikely that it would take 3 hours but if you are arriving during a commuter rush hour or national holiday ir could take 2 hours or so.
2. The Disneyland Express Bus is a full-size coach bus (like a Greyhound bus). It pulls up in front of your terminal under the GREEN overhead signs which say: "Flyaway Buses and Long Distance Vans". It is a SCHEDULED conveyance so it arrives at LAX twice per hour and leaves promptly whether it is full or not. It goes to the Disneyland Resort first and then you will either be taken on to your hotel or you will be transferred to a van for the rest of your trip. Count on 1-1/2 hours total time (assuming you are not staying at the DL Resort which would be quicker).
In choosing between these 2, the Disneyland Express bus is a little more comfortable but I would take either one that is ready and waiting. (BTW, there is a $3 discount coupon on the DL Express website -- on the coupon link, just below the photo on the home page),
3. A taxi will be the quickest and most convenient but it will cost ABOUT $90 (it depends on traffic since the meter in the taxi calculates the fare based on distance plus the number of seconds that the taxi is standing still -- in a traffic jam or at a red light).
(None of the above fares include tip (15%).
Another option is to reserve a PRIVATE VAN from either of the two shared van services. This would mean a van all to yourself without waiting for anyone else to arrive or depart from the van. The cost is about the same as a taxi, $88-$92 (+tip) but it's more spacious than a taxi and if you hit traffic, the cost is fixed (no surcharge for standing still). These have to be reserved in advance.