There is no snow mound at any of the 3 DLR hotels.
The Grand Californian is the only hotel that has a PhotoPass photographer with Santa (but not at any other time of day), and Santa only appears at that hotel for a couple of hours each night (sometime after 5 p.m. but before 8 p.m.).
The Paradise Pier has a gorgeous tree in the lobby as well, and Santa appears there (usually in the morning), but there is no PhotoPass person.
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Disneyland Hotel has a rather decorative, detailed Santa set-up/backdrop in their lobby, and I think Santa appears there before 5 p.m.-ish. No PhotoPass person, though - unless they have added one.
There are all kinds of great places for holiday photo ops with PhotoPass people - browse through the Christmas Superthread and you will get lots of ideas.
There is a PhotoPass person with Santa at the Reindeer Round-Up in Disneyland, and there is also a PhotoPass person outside at the Round-Up, for a sleigh photo op.
In California Adventure, Santa has a location in Paradise Pier by the Christmas tree, with a PhotoPass person.
You will find PhotoPass people in front of the Winter Castle in the daytime and at night - make sure to get a nighttime photo when the icicle lights are turned on.
There are PhotoPass people in front of the giant tree on Main Street (both sides of the tree).
There are cute toy soldier & sleigh photo ops/set-ups around It's a Small World Holiday, which you will see if you go back there, and at night, when the facade is all lit up, there is usually a PhotoPass person lurking around.
Downtown Disney had a holiday photo op last year, and I saw a PhotoPass person there at night (not in the daytime). Not sure if that photo op is there again this year.