How exciting you are planning to propose in Disneyland!!!
My DF did some research and talked with a ton of people at the Disneyland Resort to find out there is only a list of "suggested" places and no pre-set packages like in Disney World... most of the suggestions were cute, but very public. If you are interested, you can PM me and I can ask my DF who he contacted to get the list (I'm not sure if he still has it)- I know he called around for a good few days before he got some good info.
My DF proposed at a private dinner he set up on the 6th floor balcony (facing Disneyland) at the Grand Californian hotel... they piped in the music from Wishes to the balcony and he proposed right after the last song "When you wish upon a star." It was sooo romantic and private, but very Disney!!!

I would highly recommend working with the Grand Californian. He had a great experience with them (even after the waitress was a little slow with everything... very nice, but slow. If you do this I would ask them to make sure the waiter/waitress is attentive and knows (and can understand) the schedule for everything. You can read more about this below.)
He set up our 1st engagement anniversary dinner to be the same exact thing (this time around we had an extremely attentive and super sweet waiter who brought us engagement pins, free drinks, and everything! I don't remember his name, but he was really great!)
You might be able to get Mickey or another character to make an appearance on the balcony, but for a price of course.
You can read more about our engagement here and see some pictures:
http://www.disboards.com/showpost.php?p=18198022&postcount=10
And here are a few pictures from our 1st engagement anniversary dinner:
The balcony where the proposal took place:
When we came back to our hotel room at the Grand Californian (DF requested this through the Grand Californian):
My only suggestion would be to request flowers for the table or something. That was the one thing my DF forgot (he was so attentive on everything else that the flowers were the last thing on his mind... in the end it didn't matter, but it would've been nice

I'm kind of a traditional sap in that case)... notice 1 year later DF requested orange roses (my fav)...
Lots of luck and let me know if you have any questions!!!
