Welcome to planDisney, Laura Rose. We're so glad you found us to ask this question. I love staying at a
Disneyland Resort hotel whenever I can to stay in the magic and for the proximity to the theme parks.
You are more than welcome to walk over and use your Disneyland Hotel key to access the
Pixar Place Hotel guest entrance to Disney California Adventure Park. I've been able to use this entrance when staying at the Disneyland Hotel and found it to be super convenient. Keep in mind that there may be (busy) times during the day when this entrance may be restricted specifically to Pixar Place Hotel guests. You will also want to make sure that you have a theme park reservation for Disney California Adventure Park either as your starting park for a Park Hopper ticket or for the day for a One Park Per Day ticket.
It looks like you will be visiting during
Halloween Time at the Disneyland Resort. The spooky season is one of my favorite times to visit. I just love walking into Disneyland Park and being greeted by the giant Mickey pumpkin. I always look forward to sinking my teeth into the seasonal eats and treats and being surrounded by all of the gourd-geous decorations.
Laura Rose, I hope this is helpful as you are making your frighteningly fantastic plans. Here's wishing you a ghoulishly good time at the Happiest Place on Earth!
Michelle