Greetings, Melissa. Thanks for stopping by planDisney! It sounds like you're hoping to make a splash during your stay next month, so let's get you an answer.
Disney's Grand Californian Hotel has one of the prettiest pool areas that my family and I have ever visited, but I do understand wanting to check out the other splashtastic pool areas at the Disneyland Resort. I wish I had better news, but resort hotel guests may only use the pool(s) located at the hotel in which they are staying. Wristbands are usually given out to access a hotel's pool area, and are only provided to guests on the reservation. You will not be able to use your room key to hop to the pools at the Disneyland Hotel and Pixar Place Hotel. I am sorry if this isn't what you hoped to hear!
Melissa, be sure to check out the wonderful restaurants at the Grand Californian during your stay. My personal favorite at the moment is
Hearthstone Lounge. It's great for a casual lunch or dinner, and the French Onion Soup is one of the best I've ever had! I also love grabbing a quick snack at the Grand Californian Great Hall Cart during the day; they often have seasonal treats that are hard to pass up.
I hope this helps in your planning, Melissa. Please
let me know if you have any other questions - I would love to help!
See ya real soon,
Melissa