I've never taken one myself, but I have friends who've taken one called Super Shuttle. I'm sorry, I don't know the phone number, maybe you could do an internet search. I'm pretty sure you need to make a ressie though.
You do NOT need to make a reservation to use the Super Shuttle. Simply collect your baggage and step outside to the curb that is marked for Shuttles and Vans. There will be a person there holding a clip board and a walkie-talkie. Tell them you want to take Super Shuttle (the best of the various van services). You will probably wait 10 to 20 minutes for the van to show up, and the van is allowed to make a maximum of three stops after you get on.
Have not had any problems with Super Shuttle and been riding them for years.
Have a great time at the park! We'll be there next week
I think Judy from Boise used another service and was quite happy with it. It you can read some of her last trip report, you can find out all about it. If Judy reads this, I hope she will answer for you.
We used the Super Shuttle when we went down in '99 right after Thanksgiving (late that night). They posted a flier on the window that said "due to the peak season" they were able to make more than three stops. It took longer for us to get to the DL Hotel from John Wayne Airport than it did for us to fly down from San Francisco! Because of that, we'll never take Super Shuttle again. I suppose our experience could be unique, though.
Depends on how many people you have, you may actually do better renting a taxi-van that only stops for you. We had bad luck with the shuttle from SNA to Disneyland in February, it took longer than our flight because they stopped in Santa Ana 3 times before we got to our hotel. We took a taxivan back to the airport and it cost less for the 4 of us. Go figure! No reservations required for Supershuttle or the other similar van services. Also, we have done the AirportBus, a regularly scheduled service from teh airports to the Disneyland and Universal hotels. It wasn't bad at all, just took about 15 minutes longer due to multiple stops. The kids preferred the bus, they could see more from up high and the seats were much more comfy. I would take whichever one came first myself.