It's possible. I've done it before (I usually go down for my B-day on 12/22. I know it is normally unbelivably crowded then, but if you plan out ahead of time, get there when the park opens, stay until it closes and don't deviate from your plan. You can do it. (And maybe even with a little extra time to spare for other stuff).
in a full day you should be able to hit everything, just depends on how much patience you have for lines.......and you might have to sacrifice lunch & dinner. So if you really really really wanna get on everything.....THEN BUCK UP!
A few years ago on Christmas day, this is what my wife and I did. we got there when it opened and went on all the rides on my list below,we went back our hotel at 2:30 in the afternoon. We returned and watched whatever Christmas parade was going on then, and went on BTRR, POTC and Space for a second time.
Pinocchio's Daring Journey
Storybook Land Canal Boats
Tower of Terror
Soarin' Over California
Grizzly River Run
Very few people could have done this, but I did manage to pull it off.(with a little help from a friend) I did it with out Fast Pass or ridemax
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PRESIDENT OF THE DISNEYLAND LOOP LOVERS ASSOCIATION
Whittier, California (just a half-hour from Disneyland)
Re: How much can you do in 1 day?
Also if you want to see Fantasmic, just bring a sheet and set it out around five or whenever other people start staking out. That way your spots saved and you can come back before right before the show starts.