This has nothing to do with your specific question, but thought I'd mention that Disneyland now has free Fastpass, which allows you to get a one-hour window "reservation" time on some of the most popular rides/attractions. Apparently, it can save a lot of time. A friend just used it and said they only had to wait 10 minutes for a ride with a 75-minute line.

I also generally stay at the Hyatt Alicante. They offer a free shuttle to the park. I still always rent a car. Depending on how long you're going bus/cab from the airport is probably just as costly as car rental.