If you're members of either, both Costco and the Entertainment card websites give a decent discount. Both are cancel-able, so you can make a reservation and still keep hunting for a better deal.
Also, I'm not sure about Alamo's prices in the Anaheim area, but I'm on their email mailing list and they send out Last Minute Deals every few weeks that are often pretty good (in the past, I've canceled my Entertainment reservation for a cheaper last-minute deal from them).