We just used Thrifty for our trip... we flew into LAX. I thought it was in the terminal but once we arrived we realized none of them are... or at least none we could see. You have to go directly outside of the baggage claim and catch a shuttle bus to the rental car places.
The Thrifty shuttle was there when we went out, so of course we missed it... but another came along in about 5 minutes. Once we got to the location (about a 10 minute drive), we were checked in, in a car and on our way in less than 15 minutes. We went with the compact and without an upgrade ended up getting a PT Cruiser convertable... perfect for California (just remember to wear sunscreen). Returning was just as fast and easy, we were back to the airport with time to spare.
When you arrive, after you get your car be sure to use Mary Jo's directions to
Disneyland! They are the best!! She has them in a sticky but in case you can't find it here's a link to help you out.
This is the link to my original question, just scroll down until you get to Mary Jo's post. We just printed them out and followed them step by step. Try it you'll be glad you did!
http://www.disboards.com/showthread.php?t=1169495