Hey, I'm a newbie here, but I'm a southern cali native, and a DL passholder. Any of the hotels around the park will be fine, there are either shuttles that run to the park or it is well within walking distance to the gates.
End of May-end of August are the BUSY times, so do be prepared for a crowd.
DL and DCA, if you've never been before, will probably be 3-4 days of activity for you. But you will be in sunny southern california, there is Universal Studios, Magic Mountain, the beach...Hollywood...tons of things to do. All those would require a car, or quite the expensive taxi ride.
I believe John Wayne Airport is the closest to Disneyland, and depending on the hotel, there might be a shuttle there for you, or you could just rent your car from the airport.
Read the tips the other poster directed you to, and good luck! If you have any park specific questions or anything, I can help you out!!