Hello there Teresa! Welcome to planDisney and thank you for bringing your question to us. You must be so excited to start planning all your Disneyland Resort details.
While I've heard great things about vacation packages booked through Costco, I'm not sure how the details work. Since you made the purchase through them, I think it would be best to start by contacting Costco to see what your options are. I went ahead and did some digging and it looks as though there are dedicated Disney partners for Costco after bookings are made. I suggest calling 1-866-232-4208 to speak with Costco Travel’s dedicated Disney partners who can access the booking and possibly make changes to your vacation plans.
Once that is taken care of remember that
advanced dining reservations can be made 60 days in advance. I've heard from friends that they start seeing reservations pop up around 3:00 a.m. Pacific Standard Time. If there are reservations you aren't able to get, my other tip is to keep checking closer to your trip. I was able to secure two hard-to-get reservations for my trip this week two days before and again 24 hours before when people are more likely to change their plans and cancel.
I do hope that the phone number I shared with you helps you get the upgrade you are looking for. I absolutely love staying on property when we can. It's so convenient to be able to take a quick walk back for a mid-afternoon break, and Disneyland Resort hotels have so many great extras they provide to enjoy time at the resort hotel as well. My kids still talk about the water slide from one of our stays at
Disney's Grand Californian Hotel & Spa.
Thanks again for stopping by, Teresa. Please come back with any other questions you may have as you continue to plan for your trip to The Happiest Place on Earth!
Carrie