I usually attend a medical conference at the Anaheim Convention center, which is across the street from Disneyland. I like using SNA, but haven't flown into LAX for this conference. I don't usually rent a car, because I am really only going to the conference. You can book Supershuttle for less than $20. A Taxi trip is about $35-40 before tip. When I went to the conference, I went to DL in the evenings. You can get a resort shuttle, which will take you from in front of various resorts to the parking lot at DL, and leaves about every 20 minutes. As I remember, it was about $4 or so each way. I stayed at the Anaheim Hilton for my conference, which really is walking distance to DL, but, since I was going to be out after dark, I took the shuttle just to be safer than walking in a strange city at night. I am glad I did, because one evening there was quite a lot of police activity on the road just outside of DL. Not sure what was going on, but was glad I was on a bus, and not on foot.
Also, the hotels in Anaheim don't have shuttles to SNA, the way that O'Hare has shuttles to many of the hotels in Rosemont.